Wow! Where can I get a strait-jacket like that?

From Schiaparelli to Armani, Mae West to Richard Gere, the fashion and film industries used to cross-dress to the nines. Not any more.

While watching the cockroach-crunching scene from Francis Ford Coppola's Dracula, in which Tom Waits's Renfield munches and mumbles in his padded cell, one critic was heard to sigh, "Wow! Where can I get a strait-jacket like that?"

Film and fashion have been cross-dressing for decades - ever since DW Griffith invented false eyelashes to add a flutter to the orgy scenes in his 1916 epic Intolerance; and this often unholy alliance carries on right up to Jean Paul Gaultier's futuristic frocking for Luc Besson's The Fifth Element, currently shooting at Pinewood. Throughout the history of movies, film studios have exploited couturiers, couturiers have cashed in on movies, and both sides of the equation have joined up to tap into the public's voracious hunger for style, exclusivity and excess. Because, after all, fashion is the one thing that you can carry out of a film and take home with you. You may not be able to edit your life or re-write your dialogue, but you can look like a star. Or, as Silver Screen asked its readers in 1953, "Have you the secret wish to become a beautiful island enchantress? Well, lovely Dorothy Lamour's slinky native sarongs will soon be available to every plain Jane."

Fashion may have given the screen some of its greatest stars - Garbo, Monroe and Bardot were all ex-models - but celluloid has returned the favour with interest by kick-starting a vogue for every item of clothing from Barbara Stanwyck's snoods to Chariots of Fire's chequered plus-fours. Sometimes a series of clothes will keep on bouncing back and forth between erstwhile film and vintage fashion right up on to the catwalks of today. Take the queen's ballgowns, for instance, in MGM's sumptuous 1938 Marie Antoinette. Created for Norma Shearer by the studio's in-house designer, "Adrian", the satin gowns were inspired by the invention 10 years earlier of bias cutting by the hot Parisian designer Madeleine Vionnet. This meant that the gowns clung somewhat anachronistically, but much more seductively, to Marie Antoinette's hip. This slinky royal shepherdess caught the eye of Gianni Versace, who put Adrian's slithery bias-cut ballgowns at the centre of his Spring '92 collection. At the same time, his arch-rival Christian Lacroix was also looking back to movie versions of the 18th century, but he had set his sights on a more recent cinematic interpretation, with ribbons, corsets and bodices taken from Stephen Frears's Dangerous Liaisons.

The liaison between film and fashion may be labyrinthine, but it is this very complexity that enables it to feed into other art forms. It is now art history that Salvador Dali was obsessed with Mae West's lips, but what is less well known is that his painting - and custom-made sofa - of that famous crimson cupid's bow came out of the fashion-film fusion. In the early Thirties Mae West did not have the time to go to Paris for fittings with her favourite designer, Elsa Schiaparelli, nor could Schiaparelli leave her salon to visit the pint-sized siren in Hollywood. Ever resourceful, West therefore had her body cast in plaster and sent to Paris for Schiaparelli to cut from the legendary hourglass figure.

The couturier, however, grew so fond of what she called her "perfectly calibrated mannequin" that she moved it into the front window of her Place Vendome salon. Once there, the curvaceous cast became a Surrealist icon - especially studied by the designer's young Catalan friend, Salvador Dali. Thus the 1934 hallucinatory portrait of Mae West's Face which May Be Used as a Surrealist Apartment was born - and a thousand Dali lip-sofas were launched. Schiaparelli herself then took the cycle one stage further when, out of the cast, she created the classic perfume bottle for her scent, "Shocking" - which in turn became the prototype for Gaultier's own corseted-torso perfume bottle.

But such creative fertility has always had to co-exist with some hard- nosed number-crunching. Before the birth of cinema, the garment trade barely existed in America. There was, in effect, no fashion business. The roots of America's fashion industry initially lay in the early studios' use of locally copied couture to add glamour to an emerging star system. But what was once a nickel-and-dime sideline for a Hollywood shirt-manufacturer would burgeon into one of the great success stories of 20th-century capitalism. For, up to the 1920s, America was in deep recession. It may have been producing the goods, but its wage-poor workers could not afford to buy them. The country therefore needed to turn those workers into consumers. And Hollywood effected that change.

Nowadays critics have a tendency to complain about product-placement in films. The truth is that today's cinematic commercialism is but a pallid imitation of the product tie-ins to performing stars prevalent during Hollywood's golden era. This is how one of thousands of merchandising strategies unfolded: in 1931, MGM sent Macy's, the New York department store, some stills of Joan Crawford wearing Adrian's dress for Letty Lynton, a whole year before the cameras were due to roll. Macy's then contracted out the manufacture of the dress so that it was ready in time for the film's release. MGM, in turn, sent Macy's photographs of Joan and that dress emblazoned with the movie's title, the names of the other stars and the studio logo, as well as details of all the theatres where Letty Lynton was to appear. The result: Macy's sold half a million copies of Adrian's dress. (Surprisingly, the only vestige that remains from this sort of high-impact, watertight merchandising is Spike's Joint, the clothes store in Brooklyn owned by Spike Lee.)

We know that, way before Batman jackets, right from the beginning, the stars themselves were aware of this commercial link. Leading Hollywood cameraman Joseph Walker remembered this early film-fashion consciousness in a tale from the heyday of the City of Lights. "One Sunday, walking down Hollywood Boulevard I spotted [the press baron] William Randolph Hearst, with [his lover, the actress] Marion Davies. The couple were peering intently at a display of frocks in the window of a fashionable shop. But what caught my eye was not the star herself but the fact that she was using a cameraman's blue viewing glass. Watching her, I knew she was evaluating the gowns in the shop window - a sure way of knowing just how those dresses would photograph."

If films created the American fashion industry, though, Hollywood's treatment of couturiers has been less benign. For just as Lillian Hellman complained that the studios "clean up my plays and cut off their balls", so the studios also sanitised any creativity from the couturiers. Peter Wollen, who curated the forthcoming "Fashion in Film" season at the National Film Theatre, points out that "Hollywood served as a transmission belt taking ideas from high fashion - usually a little late - then taking them downmarket until they were acceptable to a mass audience in mid-America."

None the less, the subsequent roll call of the walking wounded from Paris to Hollywood is still impressive. The radical Madeleine Vionnet came west in the late Twenties, and her revolutionary bias cutting on the hip was successfully adapted not only by Adrian but also for Jean Harlow's silk negliges - although Vionnet herself dismissed them as "cinema satins". A few years later, in 1931, United Artists' chief Sam Goldwyn lured Chanel to the bright lights with an offer of a million dollars a year. But, as with an earlier experiment with Erte, Parisian couture did not make the transition. Chanel could not stomach the egotism of the stars and Goldwyn dismissed the results as ranging from dull to disastrous and the diminutive designer decamped for France with the comment that Hollywood was "overdressed". By this time the word was out, and although Paquin, Patou, Schiaparelli and Worth all contributed to ex-designer Mitchell Leisen's exceptional fashion film Artists and Models Abroad in 1937, none of them stepped outside of Paris.

Rather than America it was to be in Europe that high fashion would actually be allowed to show itself off, unhindered from cutting board to the cutting room without losing a stitch. Chanel gracefully moved from Renoir's Rules of the Game to Cocteau's Beauty and the Beast, providing her little black dress for both masters and their servants in the former, while her brocaded ruffs and collars turned the Beast into a sympathetic object of desire for Cocteau's fairy-tale. Others followed in Chanel's elegant wake. Givenchy dressed the gamine Audrey Hepburn on her European-based films and, in Stanley Donen's Two for the Road, Mary Quant, alongside Paco Rabanne, provided an unsurpassed document of Fifties and Sixties fashions which demonstrated how affluence alters personal style.

Now, however, the monopoly that bound fashion to film has been broken by the upsurge of other media. TV, video and multi-screened department stores provide the fashion houses with a far more efficient and direct means of showing off their latest collections. Admittedly, the Milanese designer Giorgio Armani has tried to apply a brake to this diffusing, diluting trend. His extensive wardrobe for Richard Gere in American Gigolo is now regarded as a definitive early-Eighties film-fashion statement.

Jean Paul Gaultier has also built on this heritage with his costumes - which he provided for free - on Peter Greenaway's The Cook, the Thief, His Wife and Her Lover. Here fashion fans noted characteristically witty touches such as the culinary motifs on the waiters' uniforms, as well as the stylish device of changing Helen Mirren's costumes as she moves from room to room. They were less pleased, though, with the roll call of faces and foibles paraded in Robert Altman's rambling homage to the rag trade, Pret a Porter.

Aside from these one-off examples, however, the content of most contemporary films works against the glamorous spell that couturiers attempt to weave. "Films are no longer set in high society," says Peter Wollen. "They're no longer about the sort of people who wear couturier clothes." More crucially, as Amanda Harlech, creative director of Givenchy, points out, fashion has become a victim of its own success. "Advertising campaigns have killed the use of fashion in films because the clothes now carry so much baggage with them.

"Say you recognise a Chanel suit," she explains, "you immediately think of that Claudia Schiffer advert or you'll have a print-out running across your consciousness whispering 'Chanel No 5'. Directors don't want that sort of evocative message cutting across the screen."

Harlech, who is recognised as John Galliano's muse, thinks that film can still inspire a dress or gown. She herself regularly makes up stories about old movie stars, such as Dolores Del Rio, which Galliano then uses as a springboard for his imagination. But she also observes that the partnership between stars like Mae West and Schiaparelli or Givenchy and Hepburn has been superseded by another kind of performing star.

"Musicians have taken over that role," she says. "They wear designer clothes that are identifiable with certain houses." So George Michael is associated with Versace, Clapton with Armani, Madonna - and now Bjork - with Gaultier, Courtney Love with Herve Leger and Oasis with the Stussy label.

Kurt Loder, who anchors MTV's Fashion News show, acknowledges that this change-over was kick-started by Mick Jagger and Anita Pallenberg in Ossie Clark's costumes for the 1970 movie Performance, but he believes that the switch between mediums is now complete. "Rock and fashion both ride the same idea," he says. "We're young, we're new, we're different, fuck you." Or, as Marie Antoinette's own dress designer, Rose Bertin, put it more stylishly: "There's nothing new except what's been forgotten."

The "Fashion in Film" season starts at the National Film Theatre, London SE1 (0171-928 3232) with the premiere of Isaac Mizrahi's Unzipped on 1 March and ends on 20 March