THE PARIS Opera Ballet, the oldest classical dance company in the world, has, since its inception in 1661, enjoyed a history of triumph and travail.

The triumphs -- the development of a set ballet technique and training system, the premieres of "Giselle," "La Sylphide" and "Coppelia" -- came during the troupe's first 200 years. In this century, however, the Paris Opera Ballet has taken an artistic back seat on the international dance scene.

But now the company is experiencing a revitalization, thanks in large part to the 1983 appointment of Rudolf Nureyev as artistic director. In addition to bringing his considerable charisma and box office strength, the 48-year-old superstar has beefed up the repertoire, reviving older productions, adding his own, and commissioning work from contemporary choreographers. At the same time, a gifted group of native-born dancers have come of age.

The Paris Opera Ballet's last visit to this country came in 1948, so its current New York-Washington tour is something of an event. Though the troupe performed a wide variety of dances during its New York run, Washington audiences will see only Nureyev's 1985 production of "Swan Lake."

This is no ordinary "Swan Lake," however. Without abandoning tradition, Nureyev has inserted some contemporary touches. Prince Siegfried dreams the happenings that occur on stage, and, in this rather psychological interpretation, his tutor, Wolfgang, and the evil sorcerer Von Rothbart are identified with each other and played by the same dancer. Nureyev will dance this dual role Saturday evening and Sunday afternoon.

PARIS OPERA BALLET -- Friday at 8, Saturday at 2 and 8, Sunday at 1:30, Kennedy Center Opera House.