At fifteen, Natalie Portman has already been compared to Elizabeth Taylor and Audrey Hepburn and has acted opposite Hollywood's most desirable leading men. But the star of Leon and Beautiful Girls is too clever to be caught in the trappings of fame.

Hollywood's star machine, that churning vortex which grips hold of young actors and flings them in to the soul shredder, has settled on little Natalie Portman. She is unfazed.

Movie agents and their kind use a particular voice when rubbing with their celebrities. "Hiiiii!" they will say, eyes open wide. "Great to seeee you!" Natalie, aged fifteen, knows the tone. At the swank Manhattan offices of mighty ICM, it was as though the boss's bambina had arrived for a "daughters at work" day. "Hiiiii, Natalie!" they shrieked down the corridor when she arrived. "How arrrrrre you?"

The truth is that Natalie Portman is doing very well, thank you, and is remarkably steady-minded for a girl who has already made five movies, and who numbers Al Pacino, Robert deNiro, Timothy Hutton, Gary Oldman, and Woody Allen among her co-stars. At an age when most of us were coping with spots and shandy hangovers, she has already earned a dollar sum that would not disgrace the gross domestic product of Burkina Faso.

Celebrity endorsement middlemen in spacious office suites across America finger their lower lips and feverishly click their Biro tops as they work out how best to approach this school-room cutie who has more acting ability in her little toe than Demi Moore and Jennifer Aniston combined. Hollywood scripts arrive at her door daily and fashion designer Isaac Mizrahi has called her his muse. She has not yet "done lunch" at Spago, but only because she has too much homework, and is too young to appreciate the wine list. She has her own publicity aide, lawyers, and on-set caravan, and is seasoned enough to dodge dangerous or impertinent questions. For instance, exactly how big is her bank account? "Even if I knew, I wouldn't tell you," she says crisply, with a slight tweak of the right eye to convey her disdain.

Child actors are notoriously prone to self-combustion, but Natalie Portman, far from surrendering to the stardom machine, is as composed as the single-minded little girl she played, stunningly, in Leon. That inch-perfect 1994 début performance, opposite French star Jean Reno, had people saying she was the best child actress since Elizabeth Taylor, and led to physical comparisons to the young Audrey Hepburn. The look is, in fact, more like Julia Roberts, and while it is too early to be sure how her just-budding body will turn out, she has a lean frame and is long of leg.

The original script for Leon contained a nude scene. Natalie said no. Nor would she accept a body double doing the scene. Cinema-goers would still think it was her, she said, and that simply would not do. However, she was canny enough to permit French director Luc Besson to film her navel, and to let his camera linger in a thoroughly continental way on her clothed bottom.

Ninety per cent of the scripts she receives are erotic and go straight in the bin-- or are perhaps read by her school friends, who smirk at the smut. Natalie was offered a chance to play Lolita opposite Jeremy Irons in the erotic novel's forthcoming film adaptation, but she turned it down. A part in the next Woody Allen film seemed a better career move. She has also been at work on Tim Burton's Mars Attacks! and she is scheduled to appear in Robert Redford's delayed The Horse Whisperer.

She has a hit-me-on-the-chin defiance, a dare-you quality which confronts the camera. In her latest movie, Beautiful Girls, released in Britain in November, she plays a thirteen-year-old small-town girl who is old beyond her years and who falls in (chaste) love with Timothy Hutton. She is the best thing in the picture, and amply demonstrates why people in the movie business are taking her so seriously. As her character says early on in the film, her appeal goes beyond baby-doll looks.

Although Natalie is an only child, her parents have been fastidious about not spoiling her since the day she was "discovered" in a Long Island pizza parlour by a modelling scout. They are determined not to repeat the mistakes of the parents of Macaulay Culkin, who recently announced that he was quitting films. "I've met Macaulay and he seemed a really sweet guy," says Natalie. "I felt very bad for him, but his parents' jobs were to manage his career. My parents don't use any of my money."

At home, when not reading scripts, doing her homework or cleaning dishes (she may be a movie star but she must still do her share of household chores), she spends time with her best friend Rachael. "She's into soccer and lacrosse and she's great," says Natalie. "She has a trampoline out the back where we play." This summer Natalie spent weeks away from home at camp, where she took a drama course. She did teenage things such as staying up all night, writing poems, fretting about learning her lines for A Midsummer Night's Dream and fancying the pants off various boys. "I don't think I"ve ever been in love," she says. "I'm sure I will be some day. I've had enormous crushes, although I've never been in to the Brad Pitt thing."

There are moments when the movie business appears to have her in its grip. On her fifteenth birthday, for instance, she was in Hollywood, and spent four hours putting in an appearance at an AIDS charity event. If prodded, she will talk earnestly about the meaning of life, saving the planet, and the wrongs of eating meat. She knows to be discreet about Woody Allen and Soon-Yi, and although she admits that "I've met some really beautiful people with ugly personalities", she is too shrewd to give names. Keep them for the autobiography, baby, you can almost hear an agent say.

But then the guard drops and she mimics ICM's esteemed head honcho Sam Cohen. She jumps coltishly around the room doing Lily Tomlin impersonations, and fantasizes about scribbling moustaches on the faces of dour movie moguls. She talks about squishing fruit flies, and about Noodles, her "schnoodle" dog (a cross between a Schnauzer and a poodle). Stardom can do its worst, but on current form it is not going to trip up Natalie Portman.