Bob Mackie c 1991 Gold Sequin Fringe & Lace Embellished Mini Dress
By Bob Mackie
Located in Los Angeles, CA
The combination of romantic lace, dramatic sparkle, and sculptural construction reflects the opulent occasion dressing that defined early '90s couture-inspired eveningwear, while rem...
Vintage Bob Mackie Size 12 Black + Nude Lace Crepe Off - Shoulder 1990s Dress
By Bob Mackie
Located in San Diego, CA
Beautiful vintage 90s BOB MACKIE Size 14 (runs true to size) black and nude lace + crepe cocktail off-the-shoulder 3/4 sleeves dress!
$3,600Sale Price|20% Off
Vintage Bob Mackie 80's Black Lace Fully Beaded Maxi Dress Gown US 10
By Bob Mackie
Located in Montgomery, TX
Vintage Bob Mackie 80's Black Lace Fully Beaded Maxi Dress Gown Designer size - 10 ( please check measurements).
Vintage Bob Mackie Size 8 / 10 Black and Pink Beaded French Lace Evening Gown
By Bob Mackie
Located in San Diego, CA
Gorgeous vintage BOB MACKIE black and pink beaded French lace evening gown!
Bob Mackie Vintage Elegant Black and Nude Velvet and Lace Evening Gown Size 4
By Bob Mackie
Located in Saint Petersburg, FL
Bob Mackie - Timeless and elegant best describes this black velvet evening gown with nude and black lace inlay.
1980S BOB MACKIE Black & Cream Lace Gown With Fab Bow Sleeves
By Bob Mackie
Located in New York, NY
1980S BOB MACKIE Black & Cream Lace Gown With Fab Bow Sleeves
Bob Mackie CHIC! Vintage Black Jeweled Lace Cocktail Dress w/Bow Size 6/8
By Bob Mackie, Martha
Located in Palm Desert, CA
The Bob Mackie label was removed. The Imported lace is accented with hand embelished in Mr.
Bob Mackie 1980s Black + Nude Lace Rhinestone Vintage 80s Mini Dress
By Bob Mackie
Located in San Diego, CA
Sexy late 1980s BOB MACKIE black and nude silk mini dress ! Bodice features nude silk with black lace overlay that is embellished with rhinestones.
Bob Mackie Attribution Sequin Lace Cocktail Dress, 1980s
By Bob Mackie
Located in Los Angeles, CA
This fabulous 1980's cocktail dress, attributed to iconic American designer Bob Mackie, is covered in bordeaux red metallic lace embellished with silk ribbon and iridescent sequins.
1990s Bob Mackie Black Silk, Lace, and Rhinestone Cocktail Dress
By Bob Mackie
Located in Houston, TX
Stunning black silk cocktail dress by Bob Mackie. The dress falls at the knee, has long batwing sleeves with a narrow cuff, a plunging V - neckline, and a loose pencil skirt.
1970s Bob Mackie Glamorous Navy Lace and Silk Chiffon Evening Dress
By Bob Mackie
Located in New York, NY
This Bob Mackie dress was sold in the designer penthouse of Miss Jackson's in Tulsa which has since closed its doors.
Unavailable
Size: See Description
Bob Mackie 1980s Vintage Black Lace & Sequins Illusion Dress w Paper Bag Waist
By Bob Mackie
Located in Portland, OR
This is a stunning Bob Mackie vintage black evening dress from the 1980's.
1980's Bob Mackie for Glydons Lilac Lace Peignoir Set
By Bob Mackie, Glydons
Located in Los Angeles, CA
Vintage peignoir set from Bob Mackie from Glydons is made of lilac-colored nylon lace and dates to the 1980's.
Bob Mackie 1980s Red Beaded Lace Gown
By Bob Mackie
Located in Scottsdale, AZ
Step into the spotlight with the Bob Mackie 1980s Red Beaded Lace Gown, a breathtaking masterpiece of glamour and elegance.
Bob Mackie Black Metallic Lace Ruffle Crop Top - L - 1980's
By Bob Mackie
Located in West Palm Beach, FL
Bob Mackie Black Metallic Lace Ruffle Crop Top - L - 1980's.
Bob Mackie 2pc Lace Embroidered Jacket and Skirt Set, Circa 1980's
By Bob Mackie
Located in Los Angeles, CA
This is a white embroidered lace over pastel colors jacket and skirt set by Bob Mackie, from the 1980's.
Bob Mackie Black Lace over Nude Silk Halter Dress
By Bob Mackie
Located in New Hope, PA
Glistening black lace over black chiffon over nude chiffon creates a subtle and striking contrast on this sexy halter dress from Bob Mackie.
1990’s Bob Mackie Boutique Dazzling Blue Beaded Lace Gown
By Bob Mackie
Located in Kingston, NY
An exceptional formal gown from Bob Mackie Boutique, this ice blue column dress is a testament to the designer’s mastery of theatrical glamour and intricate hand-finishing.
BOB MACKIE Pink Silk & Lace Embellished Ball Gown Size 12
By Bob Mackie
Located in Los Angeles, CA
This Bob Mackie gown is composed of pink silk with a silver embellished lace applique.
Bob Mackie Beaded Off Shoulder Lace Evening Dress Size 6
By Bob Mackie
Located in Palm Desert, CA
A vintage Bob Mackie Boutique Evening Dress that has never been worn! NWT. Purchased at Lord and Taylor in NYC. The dress is entirely hand beaded in aurora borealis beds over a metal...
BOB MACKIE Black Lace Gown with Draped Jersey Size Small
By Bob Mackie
Located in Los Angeles, CA
This Bob Mackie design is available for viewing at our Beverly Hills Boutique.
Bob Mackie Black Chiffon & Beaded Black Lace Evening Gown 10
By Bob Mackie
Located in West Palm Beach, FL
Bob Mackie black chiffon & black beaded lace evening gown marked size 10.
1980s Bob Mackie Deep Plunging Lace and Silk Crepe Cocktail Dress
By Bob Mackie
Located in Gresham, OR
A 1980s Bob Mackie cocktail dress of black silk crepe with deep plunging sweetheart neckline and illusion lace top sprinkled with multicolor ribbon flowers.
Bob Mackie Mint Silk and Lace Beaded One Shoulder Gown, 1980s
By Bob Mackie
Located in West Palm Beach, FL
Bob Mackie Mint Silk & Lace Beaded One Shoulder Gown - 12 - 1980's.
Sold
Size: Small / Small Medium
Vintage Bob Mackie Amazing Chartreuse Green + Gold Silk Chiffon Lace Gown
By Bob Mackie
Located in San Diego, CA
Amazing vintage BOB MACKIE couture chartreuse green and gold French lace and silk chiffon high neck evening gown!
1990s Bob Mackie Peach Tone Floral Lurex Embroidery Lace Strapless Evening Gown
By Bob Mackie
Located in West Hollywood, CA
This 1990s strapless gown by Bob Mackie features a sheer peach lace base embroidered with oversized lilac and sage floral motifs in metallic Lurex thread.
Bob Mackie Black Sequin Embroidered Lace Bow Shoulder Nude Lined Evening dress
By Bob Mackie
Located in West Palm Beach, FL
Bob Mackie black sequin embroidered lace evening gown with black silk shoulder ribbon bows, nude lining from the 1980s.
Black lace and purple faille evening dress with black velvet bow Bob Mackie
By Bob Mackie
Located in Saint-Ouen-Sur-Seine, FR
Black lace and purple faille ( probably rayon) evening dress with black velvet bow. Powder beige lining under the lace. Sequin embellishment on the lace. Ruffles on the hips. Zip clo...
Vintage Size 8 Bob Mackie Black Lace Sequin 1990s 90s Evening Off Shoulder Gown
By Bob Mackie
Located in San Diego, CA
Gorgeous vintage 1990s BOB MACKIE black and nude lace and sequined evening dress!
Vintage Bob Mackie Size 4 / 6 Black Nude Lace Sequin Sexy Plunging Mini Dress
By Bob Mackie
Located in San Diego, CA
Sexy vintage BOB MACKIE black, nude and silver strapless silk, lace, and sequins mini dress!
1980's Starlet Bob Mackie Lace Corset Dress Gown 30% off SALE
By Bob Mackie
Located in New York, NY
Another spectacular Bob Mackie Creation! Nude color silk Georgette covered with cream lace.
Vintage BOB MACKIE 1980 crystal embellished lace dress & jacket
By Bob Mackie
Located in Newport Beach, CA
Vintage BOB MACKIE 1980's jet black crystal embellished lace dress & jacket set.
Vintage 1987 Cher Witches of Eastwick Movie-Worn Alaia Lace Up Skirt & Crop Top
By Bob Mackie, Azzedine Alaïa
Located in Beverly Hills, CA
With the costume designer's approval, she personally requested Bob Mackie to make her a cropped top in the matching fabric.
Bob Mackie Embellished Lace Evening Gown
By Bob Mackie
Located in Cloverdale, CA
Exquisite evening gown from Bob Mackie. Featuring an embellished lace strapless top and purple silk ball skirt, this has multiple petticoats under the skirt.
Bob Mackie Sequinned Lace Evening Gown
By Bob Mackie
Located in Doncaster, South Yorkshire
Bob Mackie Vintage 1990s Sequinned Nude & Black Lace Pointed Bodice Evening Gown Estimated Size: UK 6/ US 2/ EU 34.
Bob Mackie Black Lace Cocktail Dress
By Bob Mackie
Located in Los Angeles, CA
Black cotton lace over pastel floral brushed cotton. Exaggerated shoulders are created by lace 'fins' that are supported by metal stays. Scalloped hem and boat neck. Short sleeves...
Bob Mackie Tangerine Gold Lace and Rhinestone Cocktail Dress, 1990s
By Bob Mackie
Located in Houston, TX
Tangerine form fitting cocktail (or party!) dress by Bob Mackie. The dress is thigh-length and consists of a tangerine fitted sheath dress under layers of gilded lace.
1980s Vintage Bob Mackie Black Lace Illusion Dress w Paper Bag Waist
By Bob Mackie
Located in Portland, OR
This is an absolutely gorgeous Bob Mackie vintage black dress from the 1980's.
Bob Mackie Silk Strapless Gold Lace Adorned Evening Dress and Cape Coat, 1980s
By Bob Mackie
Located in Cloverdale, CA
Bob Mackie 1980's Silk Strapless Evening Dress and Cape Coat from Neiman Marcus Incredible bezel set crystal embellished gold lace on a strapless evening dress with matching cape coa...
Vintage Lillie Rubin 1990s Amazing Fully Beaded Sequined Pearl Silk Fringe Dress
By Lillie Rubin
Located in San Diego, CA
Amazing vintage early 90s LILLIE RUBIN black beaded, sequined, and pearled silk cocktail flapper dress! Heavily hand beaded black seed beads throughout the skirt. Gold and silver seq...
$1,036Sale Price|20% Off
Size: 10
1990s Bob Mackie Size 10 Black Crepe Sexy 90s Vintage High Slit Evening Gown
By Bob Mackie
Located in San Diego, CA
Sexy, yet sophisticated 1990s BOB MACKIE black crepe bodycon evening dress! Features an elegant sweetheart neckline, with satin trim. Figure flattering silhouette that hugs the body ...
Dolce & Gabbana Spring/Summer 1997 Black Lace Maxi Dress
By Dolce & Gabbana
Located in CAPELLE AAN DEN IJSSEL, ZH
A stunning vintage masterpiece from Dolce & Gabbana’s iconic Spring/Summer 1997 collection, this black lace maxi dress perfectly balances elegance with subtle sensuality. The dress f...
Cher Bob Mackie Met Gala 1985 Silk Beaded Sequin Sheer Vintage 80s Gown Dress
By Bob Mackie
Located in San Diego, CA
Sexy 1980s BOB MACKIE 1985 silk chiffon beaded and sequin evening gown ! Very similar to the one Cher famously wore to the 1985 MET Gala with Mackie, himself. Sheer bodice with thous...
OSCAR DE LA RENTA Black Lace Cocktail Dress Ruffled Hem and Rhinestones Size 6-8
By Oscar De La Renta
Located in Los Angeles, CA
This Oscar De La Renta cocktail dress is composed of a black lace combination with nude base. Features a ruffled hem with rhinestones splashed throughout the hem. There is a center...
1970S BOB MACKIE Black Beaded Silk Geometric Cut Out Low & Backless Gown
By Bob Mackie
Located in New York, NY
1970S BOB MACKIE Black Beaded Silk Geometric Cut Out Low & Backless Gown
Roberto Cavalli FW 2007 as seen on Britney Spears Gold Embellished Mini Dress
By Roberto Cavalli
Located in Montgomery, TX
An iconic archive piece from the celebrated 2007 Roberto Cavalli for H&M collaboration, the first-ever partnership between H&M and an Italian designer. This limited-edition collecti...
Bob Mackie Elizabeth the First 1970's Black Devoré Velvet Gown with Crystals
By Bob Mackie
Located in Los Angeles, CA
A rare couture piece designed by Bob Mackie and Ray Aghayan from their short-lived Beverly Hills custom atelier Elizabeth The First. This stunning gown has been crafted from a black ...
2000s Roberto Cavalli Gold Sequin Drop Waist Flapper Style Dress
By Roberto Cavalli
Located in Beverly Hills, CA
2000s Roberto Cavalli gold dress embellished in large sequins paillette, drop waist flapper style, and racer back. Marked size 40IT fit size 4/6 Measurement: Bust fit up to 34” Wais...
Vintage Oscar de la Renta Sheer Size 10 / 12 Black Silk Chantilly Lace Gown
By Oscar De La Renta
Located in San Diego, CA
Exquisite 1990s vintage OSCAR DE LA RENTA for SAKS 5th AVE Couture black silk chiffon and chattily lace sheer evening gown ! This beautiful dress has so much attention to details. Mu...
Museum Gianni Versace Couture 1994 Gold Metal Oroton Toga Mini Dress
By Gianni Versace Couture
Located in Jersey City, NJ
This extraordinary Gianni Versace Couture dress from 1994 is a dazzling showcase of the house’s iconic innovation, crafted entirely from gold metal mesh Oroton. Designed in a toga-in...
$4,800
Size: Marked 8 but fits today's size 4
Stunning Bob Mackie Gold & Black Deco Inspired Beaded Dress with Exposed Back
By Bob Mackie
Located in Los Angeles, CA
Resurrection Vintage is excited to present a stunning vintage Bob Mackie gold and black beaded dress with a high neck, open exposed back, a center back zipper, and mini length. The d...
Gold lace and embroideries bustier evening dress with drag RG / ROMEO GIGLI
By Romeo Gigli
Located in Saint-Ouen-Sur-Seine, FR
Gold lace and embroideries bustier evening dress with jersey lining. 90% polyester, 10% elastane. Invisible zip closure on the left side. Thin padded bra. Silicon strap inside the b...
Vintage Bob Mackie Boutique Fully Beaded Fringe Evening Dress Gown M
By Bob Mackie
Located in Montgomery, TX
Exquisitely crafted vintage evening dress by legendary American designer Bob Mackie, renowned for his opulent, highly embellished creations worn by icons and entertainers. This stri...
80-s Vintage Bob Mackie Black Beaded Bolero Dress Size 6
By Bob Mackie
Located in Montgomery, TX
80-s Bob Mackie Beaded Bolero Dress Details: Color: Black/Gold Size 6 Bodice: 100% Nylon Bottom : 66% Acetate, 34% Rayon Condition: Excellent
Valentino F/W 2003 Black Velvet 20s Inspired Beaded Gatsby Maxi Dress Gown US 8
By Valentino
Located in Montgomery, TX
Valentino Black Velvet Beaded Maxi Dress Gown F/W 2003 Runway Collection US size - 8 Black velvet 20s inspired Gatsby dress finished with lots of black onyx cabochon and crystals ove...
Victor Costa Strapless Dress
By Victor Costa
Located in Alford, MA
One of Victor Costa's best designs, this strapless cocktail/evening dress is fashioned of white satin and black velvet alternating horizontal stripes with fitted bodice leading to an...
Thierry Mugler Military Green Wrap Dress 1980s
By Thierry Mugler
Located in Water Mill, NY
A fabulous forest green wool military influence dress by Thierry Mugler. It has a small stand up collar, long sleeves with cuffs and 2 bodice patch pockets. The dress skirt wraps ac...
$575
Size: Small - Medium
Pretty 90s Rozae Nichols Floral 3 - D ' Autumn Harvest ' Silk Dress w/ Appliqué
By Rozae Nichols
Located in San Diego, CA
Pretty 1990s silk dress, by Rozae Nichols! Gorgeous neutral hues, with a unique floral print throughout. Flattering silhouette, with silk floral puff appliqués at left shoulder. Asym...
$475Sale Price|20% Off
Size: Small
Rene Ruiz Couture Black and Nude Strapless Silk Net Overlay Bustier Corset Top
Located in San Diego, CA
Gorgeous and sexy new RENE RUIZ black and nude strapless silk ruched bustier / corset! Features a nude silk backdrop, with a black net ruched overlay. Hidden zipper up the side with ...
Ralph Lauren Collection Italian Pearl Gray Silk Charmeuse Draped Cocktail Dress
By Ralph Lauren Purple Label
Located in Morristown, NJ
Barbara Walters Provenance Ralph Lauren Collection Pearl Gray Silk Charmeuse Draped Cocktail Dress, Made in Italy An exceptionally elegant Ralph Lauren Collection cocktail dress in ...
1990s Michael Casey Silk Ombre Botanical-Patterned Strapless Gown W/ Train
By Michael Casey
Located in Gresham, OR
A lovely 1990s Michael Casey silk ombre botanical-patterned silk chiffon strapless gown with ruching and gathering at bodice. Asymmetrical delicate bronze toned bamboo leaf beaded g...
BOB MACKIE Green Chiffon Flower Embellished Gown Size 2 4
By Bob Mackie
Located in Los Angeles, CA
This vintage Bob Mackie gown is composed of a light green mint hue silk chiffon. The upper bodice features an embellished center front and short sleeve, with a floral pattern. There ...
NWT 1990s Thomas Steinbruck Size 12 Black Gray Ombre Silk Vintage 90s Gown Dress
Located in San Diego, CA
Stunning brand new with original Bergdorf Goodman store tags still attached 1990s THOMAS STEINBRUCK black and grey silk evening gown! This rare find is so flattering on. Deep plungin...
Bob Mackie Black Mesh w/ Blue Beading Long Sleeve High Neck Gown Circa 1990s
By Bob Mackie
Located in Los Angeles, CA
Bob Mackie Black Mesh w/ Blue Beading Long Sleeve High Neck Gown. In excellent condition Measurements - Size 10 Dress Length: 61 Inches Bust: 24 Inches Hip: 24 Inches Shoulder...
THIERRY MUGLER Late 1990s Soft Mocha Lace Gown
By Thierry Mugler
Located in 上海市, Xuhui district
Juding from the S/s 1999 haute Couture runway pic (please see the reference in picture No. 2)they look similar so it might be from that era. NOTE: the material is very stretchy so i...
Versace Silk Cut out Back Dress
By Versace
Located in Water Mill, NY
A beautiful pink silk dress from Versace. It is is a simple sleeveless sheath from the front. The back is exposed from the shoulders to low back with the exception of draping framin...
Dolce & Gabbana Lace up Silk Dress
By Dolce & Gabbana
Located in Water Mill, NY
A beautiful stretch silk leopard print dress from Dolce & Gabbana. The bodice has adjustable straps, functional and adjustable side lacing through to the hips plus rows of top st...
CHRISTIAN DIOR by JOHN GALLIANO Vintage Lilac Tulle and Lace Dress US Size 4
By Christian Dior
Located in Nice, FR
CHRISTIAN DIOR by JOHN GALLIANO vintage lilac tulle and lace dress. From the CHRISTIAN DIOR Spring/Summer 2008 Collection. This lilac lace dress embodies the romantic and theatrica...
1950s Maurice Rentner Women's Light Creme Sequin Cocktail Dress
By Maurice Rentner
Located in Beverly Hills, CA
Elegant 1950s Maurice rentner light creme cocktail dress with iridescent sequin. Dress comes with silk belt. Size: 4 / small Measurement: Bust: 34 inches / Waist : 26 inches / dre...
1970s Victorian Inspired Wool Challis Autumnal Fall Vintage 70s Maxi Dress
Located in San Diego, CA
Beautiful 1970s Victorian inspired Autumnal lightweight wool challis long sleeve maxi dress ! Features warm tone of khaki, brown, red, burgundy, green and orange. Printed flowers and...
Elegant French Art Deco Sequin Gown
Located in New York, NY
Elegant and timeless French Sequin Art Deco Gown sewn on cotton tulle. Nude iridescent gelatin sequins cover the entire gown completely. There are sequined Art Deco diamond motifs ab...
Vintage Bob Mackie dresses are a fashion favorite, and with good reason. The legendary Monterey, California–born fashion designer has accrued an enviable list of awards that speak to his unparalleled influence on costumes for screen and theatrical performances: Mackie has nine Emmy awards to his name, a Tony award, a CFDA Lifetime Achievement Award, three Academy Award nominations and more.
As a child, Bob Mackie was enamored of Portuguese-born Brazilian dancer and actress Carmen Miranda. The love of film shared by his sister and mother proved contagious for Mackie, and he marveled at the richness and beauty he found in ballet. He wasn’t interested in fashion so much as he was in entertainment and went on to, fortunately, find work in television during the 1960s, specifically in programming that seemed to encompass all of what he’d grown to love about the arts.
As a fashion sketch artist, Mackie collaborated with Hollywood’s greatest costume designers, working with the legendary Edith Head at Paramount Studios as soon as he’d finished school. From there, he secured work with French-born, Hollywood costume designer Jean Louis, sketching the iconic Louis dress worn by Marilyn Monroe when she sang “Happy Birthday, Mr. President” to John F. Kennedy in 1962.
Mackie would spend most of his career as a costume designer, creating iconic pieces like the Gone With the Wind parody costume (currently in the Smithsonian) for The Carol Burnett Show — where he worked for more than a decade — and campy, opulent dresses for The Cher Show on Broadway, for which he won the Tony award (he also designed bedazzled stage costumes for Sonny and Cher's 1976–77 run at Harrah’s Lake Tahoe). But he had a considerable influence on mainstream fashion as well.
The figure-hugging, feathered and fringed gowns and cocktail dresses Mackie created were worn by stars like Cher and Diana Ross on the red carpet and concert tours. Similar designs of his — dazzling evening dresses of black or vibrant red silk, some beaded with rhinestones or embellished with ostrich feathers or navy blue sequins — made their way into his mainstream fashion collection. His ready-to-wear line debuted in 1982.
Bob Mackie has always said that his clothing was “for the woman who is not afraid to be noticed,” and any woman in one of his signature dresses would definitely turn heads. There is sparkle and an element of grandeur in his garments, whether they were crafted for singer Elton John, a universally renowned fashion icon in his own right, or the woman next door, donning one of Mackie’s spectacular creations and feeling like a movie star herself.
Shop vintage Bob Mackie day dresses, suits and more on 1stDibs.
With entire museum exhibitions dedicated to examining fashion designers and their creations, we’re finally recognizing that costuming is art. Evening dresses over time have conveyed specific statements about social class, position and beliefs. Fashion is a powerful means of self-expression, and sophisticated vintage evening dresses and gowns by our favorite couturier play no small role in making us feel wonderful but, perhaps more importantly, making us feel like ourselves.
In the 16th century, dresses and gowns were so important that England's Queen Elizabeth I defined rules about what dresses women could wear — guidance included long skirts and fitted bodices. Forward-thinking designers have responded to this history.
Gabrielle “Coco” Chanel reimagined traditionally masculine garments for feminine shapes, and her elegant evening dresses and gowns promoted comfort and grace in women’s wear that had been dominated in the previous century by layers of fabric. Christian Dior's gowns celebrated luxury and femininity in the late 1940s — and gave to women the gift of glamour they’d lost in the miserable years of the war. French fashion designer Yves Saint Laurent introduced innovative and highly coveted dress designs in the 1960s while at the same time challenging sexist stereotypes about which members of society could wear tuxedos.
Works by unconventional British designer John Galliano — featured in houses like Givenchy and Dior — redefined limits that dressmakers faced in terms of material, construction and vision during the late 20th century. From his embroidered absinthe-green Oscars gown for actress Nicole Kidman to the iconic sleeveless Dior newspaper dress that Sex and the City’s Carrie Bradshaw made famous, Galliano’s intricate and multifaceted work is reliably collectible and newsworthy
Today’s designers target an increasingly broad audience with their boundary-crossing work, and their tendency to play off of each other’s ideas means that every walk down the runway is also a walk through an entire history of fashion design and dress craftsmanship.
Whether you gravitate toward backless maxi dresses or silk charmeuse gowns by Alexander McQueen or embellished, ruffled floral-print designs by Chloe or Versace, there is an extraordinary collection of vintage and designer evening dresses and gowns waiting for you on 1stDibs.