Rudi Gernreich, 62, one of the nation's leading fashion designers who won fame and notoriety for his 1964 design of the topless bathing suit and won further attention for popularizing the miniskirt, died of cancer yesterday in Los Angeles.

Perhaps this country's leader in avant-garde fashion, he had worked since the 1950s to free American women from the iron hand of haute couture by creating colorful and free-flowing clothes. In addition to the miniskirt and topless swimsuit, he pioneered the use of vinyl, knit tank suits, colored stockings, the see-through blouse and the no-bra bra.

Other of his dress designs featured clashing stripes and dots, bold geometric patterns and large holes cut in the most surprising places. He was in the forefront of the "unisex" fashion movement, once telling a reporter that "When men and women borrow styles from each other, it makes fashion more interesting."

Since the 1970s, his projects have included the thong bathing suit, which nearly did for the body's bottom what the topless suit had done for the top. He also worked on body coverings that can be worn as both underwear and as costumes by themselves and something he called the first unisex perfume.

His most famous, if not most successful creation, the topless swimsuit, was created almost by accident. During a 1964 interview with a reporter from Women's Wear Daily, he casually remarked that during a recent vacation on the Riviera he had noted an enormous number of women sunbathing while clad only in their bikini bottoms. He predicted that the logical outcome of all this was a "topless" suit.

The result of this interview was an avalanche of publicity and requests from serious buyers for just such an item. Mr. Gernreich said he decided to develop the suit before someone else did. Photographs of his creation, worn by his favorite model, Peggy Moffitt, brought on a storm.

The Kremlin and the Vatican, institutions not given to fashion commentary, attacked the suit. American clergymen of nearly all creeds and denomination joined the chorus. Law enforcement organizations both here and abroad allowed as how the suit would not be allowed on their beaches. Incredibly enough, the suit sold. New York's B. Altman & Co. alone sold more than 3,000.

If the miniskirt was not as striking an innovation, it was certainly more widespread. Hemlines were hovering about three inches above the knee in the mid-1960s, when Mr. Gernreich began his artistic campaign that saw them rise to about 12 inches from the knee -- a giant foot for mankind.

Also in the 1960s, Exquisite Form, a leading brassiere manufacturer, asked Mr. Gernreich to design a bra. His "no-bra" bra was less rigid and more natural looking than traditional brassieres.

Three more entries in that category followed: the "no-sides" bra created for dresses with deep armholes, the "no-front" bra for slit-to-the-waist dresses, and the "no-back" bra anchored about the waist.

Mr. Gernreich's personal wardrobe also was unique. Among his favored costumes was a unisex outfit, unzipped to reveal a necklace of teeth carved from elephant tusks, Gucci loafers sans socks, and a plentitude of bracelets. A favorite jacket was made of the skins of Burmese water snakes.

Rudolf Gernreich was born Aug. 8, 1922, in Vienna. His father, a hosiery manufacturer, died when Mr. Gernreich was 8. His interest in fashion began while he was working in an aunt's dress shop. His sketches of clothes and fabrics brought him an offer, which he turned down, to work in London at the age of 12.

He and his mother fled Europe in 1938 and settled in Los Angeles. He attended Los Angeles City College and the Los Angeles Art Center School then was a dancer and costume designer with the Lester Horton Modern Dance Troupe. He left that organization to become a free-lance dress designer. In 1951, he and Walter Bass, a clothing manufacturer, formed a partnership. They became known for their line of loose fitting, tightly belted dresses. In 1959, Mr. Gernreich dissolved the partnership and formed what became Rudi Gernreich Inc., with offices in Los Angeles and showrooms in New York.

Mr. Gernreich was the recipient of a host of awards. They ranged from membership in the Coty American Fashion Critics Hall of Fame to the 1956 American Sportswear Design Award from Sports Illustrated. He also received Brazil's Fenit-Industria Textil award and Italy's Mare Moda-Tiberio D'Oro. He was also singled out for honors by Neiman-Marcus Co., Robinson's and Filene's.