Temperatures fell below freezing in New York City on the January night that Fifth Avenue department store Lord & Taylor held a party to launch Oleg Cassini's new line of dressy jeans and tops. Yet generations of bundled-up fans, numbering 700, came to cheer the designer 50 years after he first appeared in the store's windows. Says Lord & Taylor exec Lavelle Olexa: "I heard one woman say, 'I was never part of his life, but he was always part of mine.' "

Cassini, 91, has been influencing America's closets ever since he began outfitting stars like Lana Turner and Ava Gardner, and inspired women to dress like their First Lady, Jackie Kennedy. Current celebs like Renée Zellweger and Jill Hennessy still turn up in classic Cassini on the red carpet. Today the designer remains youthful—he took up competitive harness racing at age 80 and dates a woman more than 50 years his junior—and busy. Besides the new line, he also sells 50,000 wedding gowns a year. "My preoccupation," he says, "is to make the woman look beautiful."

Testament to that are photos of him with famous women he has loved and clothed that line the dark-wood walls of his town house on New York City's Gramercy Park. "I created the Grace Kelly look," he says, turning to a picture of the actress, to whom he was engaged before being beat out by Prince Rainier of Monaco. "She dressed like a schoolteacher. I put her in elegant, subdued dresses." There are shots of Jacqueline Kennedy, who made him, he says, "the first celebrity designer—ever." (See box at left.)

The son of a Russian count and an Italian countess (he is actually Count Oleg), Cassini grew up with an appreciation of luxury—and reversal of fortune, after his family was forced to flee Russia and traveled from country to country in his early years. "My father dressed impeccably," says Cassini. "He was quite unprepared for life after the Revolution." In the early '20s, his mother became a dressmaker in Florence. A promising art student, he helped her with sketches.

In 1936 he came to New York, where he spent his thin salary on nightlife at the Stork Club and El Morocco. After a brief marriage to an heiress, he moved to Los Angeles, landing a plum job in Paramount's wardrobe department. He was soon dressing stars and dating through the studio rosters—Susan Hayward and Betty Grable were among those who succumbed to his continental charms. But Gene Tierney (later the star of Laura) won his heart, and they married in June 1941. (They had two daughters: Daria, born deaf, blind and mentally retarded, has lived most of her life in a school for people with special needs; Christina, now a mother of four, lives in Paris.)

In 1942 Cassini became a U.S. citizen and joined the Army, serving in the cavalry at Ft. Riley, Kans. Back in Hollywood after the war, his circle included Marilyn Monroe ("the sweetest marshmallow" he calls her). But his heart was in fashion, not costumes, and in 1949, Cassini returned to New York. The decision cost him his marriage. (After the split, Tierney dated the then-single Jack Kennedy.) He launched his first line in 1950, "a look inspired by military uniforms but always sexy," he says. Cassini was not only successful; he also displayed a star quality he had gleaned from Hollywood. "It was all about manufacturers and stores [in the '50s], not designers," says designer Joseph Abboud. "He brought glamor."

After the Camelot years, Cassini expanded into menswear and pioneered licensing, making a fortune putting his name on swimwear, cars and raincoats. Now he stays in the business simply because he loves it: "I don't have to prove anything. I'm not doing anything for money." He is particularly proud of his wedding gowns (priced from $1,200 to $25,000), because his customers are young. "I'm not the designer of their mothers!" he says. "I'm the designer of tomorrow's girls."

He works almost every night until 8 p.m., keeps current on music (P. Diddy is a favorite), often dines out (Japanese food, he says, is "the perfect fare to keep in condition"), drinks only red wine and has the same breakfast nearly every day: salmon with pomegranate seeds, and espresso. Then there is his lady friend of 10 years (yes, she was in her 20s, he in his 80s, when they met), about whom he is terribly discreet.

Diane von Furstenberg, who presented him with a Council of Fashion Designers of America special tribute in 2003, has her own take on the secret of Cassini's perpetual youth: "He loves women and it shows in his clothes. He views the world through happy glasses."

By Allison Adato. Natasha Stoyoff in New York City

  • Contributors:
  • Natasha Stoyoff.