Audrey Hepburn first came to Givenchy to ask him to make her costumes for the film "Sabrina."

Deeda Blair sought out Givenchy after seeing Audrey Hepburn in "Funny Face."

After Cristobal Balenciaga shut down his couture house, he literally took Bunny Mellon by the hand and steered her to his friend, Hubert de Givenchy.

Many of the elegant women of the world, who care deeply about clothes, have put themselves in the hands of Givenchy, whose 30th anniversary as a couturier was celebrated this week at a gala benefit in New York, marking the opening of the Fashion Institute of Technology's "Givenchy: Thirty Years." (The retrospective exhibition is open to the public through Oct. 2.

Givenchy had expected to see Katharine Hepburn when told a Miss Hepburn would be coming to speak with him. "We knew little of Audrey Hepburn in France at that moment, when it took at least six months for an American film to get to Paris," Givenchy recalled in an interview earlier this week. After "Sabrina," Givenchy made Hepburn's clothes for several of her films, including "Breakfast at Tiffany's," "Funny Face" and "Bloodline." The friendship has led to some of the designer's best works and the actress' most memorable appearances.

"Audrey knows everything that is good for her. She gives me direction. She is definite," says Givenchy, 55, whose L'Interdit perfume was once owned solely by Hepburn. Later it became the first actress/designer perfume, much in the way Catherine Deneuve and Chanel work today.

"If you want to express yourself, it is difficult to be by yourself," says Givenchy of his friendship with Hepburn and other clients. "You must have people around you who understand the same music. It is like being the chef d'orchestra. They need you but you need them desperately."

"What is exceptional is the quality of everything he does, the material, the sewing," says Bunny Mellon, who confesses she was nervous when Balenciaga took her to meet Givenchy--though the designer quickly put her at ease. "He is unusual in that he adapts to the client's need, the color the client likes," says Mellon.

Givenchy once told Deeda Blair she already owned enough suits and coats and that it was time for her to try something more informal. He suggested a gray skirt and coat with a brown sweater, recalls Blair. "He made me my first French suit, in turquoise wool with covered buttons, and very architectural looking," she remembers. She wore it at least five years, she says, and other Givenchy creations much longer.

She also shopped at Balenciaga across the street. "The clothes were so related that I bought my wedding dress at Balenciaga and found the most unbelievable confection of a hat at Givenchy" that was dyed to go with the dress.

"To be a couture designer is not only to create dresses but to adapt your line to your private customers," says Givenchy. "It is why couture is expensive. You are like a doctor."

The reward, says Givenchy, comes when the customer tells you of the success of the dress. Like the note from Jacqueline Kennedy, who wore his white gown and coat to a dinner with President Kennedy and Charles de Gaulle at Versailles. In the note, Kennedy made a sketch of herself in the coat and related happily that de Gaulle had said she looked like a Watteau. The next day she called the designer to the American embassy to show off how she looked in a pink fitted coat and matching pillbox he made for her.

Then there was the letter from the singer Frederica von Stade: "M. Givenchy. I have the feeling that I sing better when I wear your clothes."

Givenchy grew up in Beauvais, near Paris, the grandson of the art-collecting curator of the Beauvais tapestries. As a boy, the designer loved the fabrics his mother chose and admired designs in the fashion magazines she had at home.

It was Cristobal Balenciaga whose designs he admired most. "For me it represented the architecture, the simplicity of fashion," recalls Givenchy as he walks through the retrospective exhibit, which includes designs once worn by the duchess of Windsor, Princess Grace of Monaco and Princess Caroline, Jacqueline Onassis, Bunny Mellon and Deeda Blair. "It was my idea to knock on the door of Balenciaga with my sketches."

But he was told Balenciaga would see no one. So, at age 17, he took his sketches to the new house of Jacques Fath, who hired him at once. Later, Givenchy worked for Elsa Schiaparelli. "At the beginning I wanted to be a good assistant. I didn't think I had the kind of name good for a couture house--too long and complicated," he laughs.

When he learned enough--"You never finish learning"--he opened a small house, in Paris in 1952. He started with a small collection of blouses and skirts, a far cry from the Dior new-look style that dominated Paris at the time. "It seemed to me to be the future for fashion." But pushed by the critics, he put aside the sportswear for the moment and made a couture collection. It was so successful he was able to open a larger salon on the Avenue Georges V across the street from his idol Balenciaga.

The two became friends. Balenciaga made the unorthodox suggestion that they view each other's collections. "I think that is what a designer and a friend must be," Balenciaga told him. As they sat together at the Givenchy show, Balenciaga gave him pointers. "He told me, 'Hubert, I love your coat but you must give the women more room for comfort. A woman must move very easily in her clothes. It is not enough to have a coat or dress that is beautiful.' "

Givenchy welcomed the advice. "I had never the opportunity to learn the details of making a coat, only to sketch what I liked." There was more advice from Balenciaga: "The dress must follow the body of the woman, not the body following the shape of the dress." Givenchy quotes Balenciaga in French, to make sure the idea is not missed.

Even now, of each new collection Givenchy asks himself, "What would Cristobal think of this? . . . Is this an honest design? Is it more than it needs to be?" Occasionally, he'll ask one of the late designer's employes, who now work for him--like Gilbert, a fitter--if Mr. Balenciaga would like, say, a certain coat. Gilbert usually responds positively.

The tall, white-haired, statesmanlike Givenchy works in the same white jacket that was a Balenciaga trademark. It fits loosely and has huge pockets to hold scissors and pins. The first jacket he ever wore was made for him by Balenciaga, who also made one for Yul Brynner. "Can you imagine having a jacket made for you by Balenciaga?"

Givenchy won't say how big his business is--only that there are ready-to-wear boutiques in 20 stores (including Garfinckel's in Washington), and licensees including menswear, jewelry and perfume. Just added are fabric designs for home furnishings. Interior decor for the Vista International Hotel, planned for Washington, is in the works.

For relaxation, Givenchy retreats to Jonchet, where he owns a 17th-century chateau with formal gardens he himself designed in the manner of one he saw in Venice. He swims laps in his pool with his golden retriever, Sarah. In New York, he visits Studio 54. "I love to dance and I love to see people dance. It is good exercise," says the designer. "It gives you a kind of energy."

Givenchy circles the retrospective exhibit before the opening, checking each garment, adjusting a collar or a belt, fixing a skirt, each time removing his shoes before stepping on the platform where the clothes are displayed. It pleases him that all of the clothes would be appropriate to wear today. "It is unjust to wear clothes just for one season or two," he says, pointing to two similar tunic dresses--one from his current collection, the other made almost 30 years ago. "You must cherish your clothes.