Vladimir Derevianko. Six years ago, one of the Bolshoi Ballet's brightest young stars fled his country - not for artistic reasons, but for love of an Italian ballerina. He has been dazzling Western audiences ever since.

When a 10-year-old boy from Omsk, Siberia, decided to give up his violin lessons and concentrate on dancing, little did he dream that one day he would leap across the Iron Curtain and become a one-man diplomat for dance in Western Europe. Vladimir Derevianko, a graduate of the Moscow Choreographic School and a former soloist with the Bolshoi Ballet, has been dancing on his own in the West since 1983. He is a recipient of the Junior Grand Prix gold medal (awarded only twice before - to Mikhail Barish-nikov and Patrick Dupond).

But unlike Barishnikov or Rudolf Nureyev, who fled the Soviet Union for artistic reasons, Derevianko left his home for romantic reasons - to be with his Italian wife.

In 1971, Vladimir's teacher in Novosibirsk, recognizing the young boy's talent, suggested he apply to study in either of the country's ballet capitals - Moscow or Leningrad. The 12-year-old dancer and his mother soon moved to Moscow. Training alongside Vladimir at the Bolshoi school was an Italian exchange student, Paola Belli. Eleven years later, in early 1982, the two were married in Moscow. Paola was able to travel freely back and forth between the two countries, but Vladimir was not.

So when the Bolshoi went on tour to Italy that summer, Vladimir did not return. ``We just decided to stay,'' he explains. ``We didn't tell anyone of our plans. It was not a political scandal. It was a new chapter in my life.''

A slight, wiry, Marcel Marceau look-alike, Dere-vianko had been a favorite with Moscow audiences for his musicality and flexibility. Early on he was given star parts in the Bolshoi repertoire - though not all the time. ``One day I would dance the `Nutcracker' Prince, the next I would be one of the slaves in `Spartacus,''' he admits. ``It was good for me; you learn so much from being in the corps de ballet.''

His fastidious technique - sharp clear steps, firmly pointed toes, and natural turnout - were evident in everything he did. But it was his final arabesque as the Butterfly Chaser in Vladimir Vasiliev's ballet ``These Charming Sounds'' that made everyone sit up and take notice. After stalking an imaginary butterfly, he saw it settle on the ground. Slowly he leaned forward, reaching out with his net as his leg rose higher and higher until it made a perfect line with his supporting foot. There he balanced, smiling at the audience. It is a position occasionally perfected by a ballerina, but few men have such elasticity and wide splits.

Derevianko is now a member of the Zurich Ballet and has had two ballets - ``Firebird'' and ``Rouge et Noir'' - created for him by the ballet's director, Uwe Scholz. Since coming to the West, he has been a guest artist ``with many great companies,'' he says, the London Festival Ballet, La Scala in Milan, John Neu-meier's Hamburg Ballet, the Ballet de Nancy, and even the Tokyo Ballet. Recently he danced at the Opera House in Nice in a new French ballet, ``Egonie,'' choreographed by 22-year-old Gerard-Michael Bohbot and based on the life of Austrian artist Egon Schiele.

To these companies Dere-vianko has brought a refinement and professionalism. Noted London critic Clement Crisp called him an ``artist of darting brilliance, both technical and dramatic.''

Says Derevianko of his success: ``I was so fortunate at the start of my career. I started to dance with a legend. The Bolshoi's Vladimir Vasiliev is one of a handful of truly great dancers in the world today. ... I tried to take everything he told me and work on it. Vasiliev invited me to dance in his ballets `Icarus' and `Macbeth,' and you can imagine what joy I felt when recently I received an invitation to dance with him again in Naples.''

The occasion was the 250th anniversary of the San Carlo Theater in Naples. ``I told no one in case it didn't come true,'' says Derevianko. ``It was a mini-glasnost for me - the first time I got to dance with a fellow Soviet since I left.'' In a triple bill program directed by Vasiliev, Derevianko danced the leading role of ``Paganini'' and the Peruvian in ``Gaite Parisienne.''

``I'm not very interested in returning for a visit to the Soviet Union even if glasnost invited me,'' Derevianko says. ``But, of course, I would love to see my mother. We wish she could come to Italy for a holiday - we've invited her, but so far she hasn't received permission.''

Derevianko's busy schedule is taking him to Japan again. Then he's off to Paris, Italy, and the south of France, before beginning a tour with the Zurich Ballet.

``My diary is full for many months to come,'' he says. ``I just dream about holidays - I had one three years ago. But it's now or never and I want to dance now.''