The avant-garde of the 1950s and '60s are coming to Washington at last, as the old masters of the '70s.

"Old Master! Brrrr!" Robert Rauschenberg shuddered, despite the balmy breezes at his Captiva Island, Fla., studio, to think that at age 54 he had already been thrust past middle age into old masterhood.

With Jasper Johns, 49, Roy Lichtenstein, 56, Ellsworth Kelly, 56, and Willem de Kooning, 75, Rauschenberg will be one of five artists featured in the 36th Biennial Exhibition of Contemporary American Painting -- known as the Corcoran Biennial -- which opened yesterday.

"I wonder how De Kooning feels about showing with all of us upstarts," chuckled Rauschenberg. De Kooning is the acknowledged master and leading survivor of the generation of Abstract Expressionist painters that catapulted American art to center stage in the early '50s -- a decade before the other painters in the show transformed the art of the '60s.

It will surprise others, besides Rauschenberg, that the enfants terribles of the '50s and '60s have so swiftly become the old masters of today. But it is even more surprising, in the 20 years since Jasper Johns painted his targets and flags, that few better painters have emerged, at least in the view of Corcoran associate director Jane Livingston, who selected the show.

"Painting is just not as good now as these painters were 10 years ago," she says. "These artists have been around a long time, but they've had the courage and stamina to continue to take risks and sustain the quality of earlier work. They've had their ups and downs, but for me they are still the best artists painting today."

For Washington the choice of these painters, each represented by six large, new works, is particularly felicitous because only one of them has ever had a major show in this city. In 1976, a large Rauschenberg retrospective was organized by the National Collection of Fine Arts. The others have been represented here only by scattered examples in small shows and in other Corcoran biennials. None of their recent major shows or retrospectives have come to Washington, though they have circled the globe.That appalling lack has been filled, if somewhat belatedly and only in part, by this exhibition.

Since the Corcoran biennials began in 1907, they have served as State of the Union messages about American painting -- barometers of what was going on all over the country as far as laying paint on canvas. Boring or sensational, on the mark or off in the judgment of subsequent art history, the biennials have managed to document every major development in American painting, from Thomas Eakins, John Singer Sargent, Mary Cassatt and John Sloan, to Abstract Expressionism, Minimalism and the Washington Color School.

Originally, the biennial was largely juried, open to all who wished to enter, though most biennials also had a section for invited artists. In 1951, the invitational section became dominant and continued to dominate until 1969, when the jury system was abandoned altogether, and the biennial became the director's or curator's personal statement about contemporary American painting.

Before making her first statement in the 1977 biennial, Livingston, then a new curator at the Corcoran, traveled all over the country, sweeping out every corner and shaking out every rug in the provinces in search of hitherto undiscovered talent. As that biennial made clear, there wasn't much left to be discovered, or if there was, Livingston didn't find it.

If the 36th biennial is different and more interesting than the last, it makes essentially the same point -- for Livingston there are still no worthy successors to old masters like De Kooning and middle-aged masters like Rauschenberg, Johns, Lichtenstein and Kelly among the current crop of American painters.

Could it be that she has found no peers for them because many of the best new minds and imaginations are working in media other than paint? That is the central question posed by this biennial, as it has been in every biennial since 1971. The obvious is becoming more difficult to evade.

The curatorial approach to this show is as telling about the late '70s as the art itself, which, rather than being revolutionary in any way, is an extension and refinement of '60s ideas. Livingston, too, has eschewed the need to be "innovative" and has put together a show based on timetested values of quality. As a result, this could be the best Corcoran biennial in years.

"I think this biennial is the most exciting show I ever heard of," said Rauschenberg, "with unseen pieces, all new work, pulling all this art together in this confrontation."

The opening will also be a reunion for old colleagues. "We all used to be very good friends, you know, but success separates people. You'll see some real theater that night," said Rauschenberg. "I told Jane Livingston I'd come even if I wasn't in the show!" CAPTION: Picture 1, Willem de Kooning

Dutch-born Willem de Kooning, white hair flying, can still be seen riding his bike to the beach at East Hampton, N.Y. Since 1962, he has lived and worked in a studio not far from the cemetery where his colleague Jackson Pollock is buried. Though De Kooning dropped out of sight in the '60s, he surfaced again last year with 100 new paintings at the Guggenheim Museum -- many with landscape overtones -- and several even more powerful new sculptures in bronze. "De Kooning is off the treadmill and has hit a new high in his late work," says Jane Livingston.,De Kooning -- Carl Paler; Illustration 1, no caption, De Kooning -- "Untitled l," 1978; Picture 2, no caption, Rauschenberg -- "Crystal Hive," 1978; Picture 3, no caption, "Credit Blossom," 1978; Picture 4, Robert Rauschenberg

"What's different about my art right now is that when I was getting ready for the 1976 retrospective, I said to myself, 'If you live through this I'll let you do whatever you want for a while, whether you've done it before or not.' I just felt like getting up to stretch after feeling so constricted by the chronology and the history of my work."

So Robert Rauschenberg's new works, called "Spreads," are full of what he calls "echoes" of the retrospective, images and materials from earlier works which he has given himself permission to use again.

One piece, "Credit Blossom," incorporating sections of a patchwork quilt, will inevitably conjure memories of his famous "Bed" of 1955.

"You might say these works are more formal -- 'classic,' that's a nice word," he agreed when pressed.

"But don't get too comfortable, because I'm getting too comfortable, and when I know what I'm doing, I do something else. I'm going to tear off any minute now!" Kauschenberg -- Bill Thompson; Illustration 2, no caption, Lichtenstein -- "Reclining Nude," 1977; Picture 5, Roy Lichtenstein

"For a long time I've been dealing with other art as my chief subject matter," says Roy Lichtenstein, the most enduring of the pure "Pop" artists. "These paintings deal with surrealism -- not one specific artist, but with the general style. This has allowed me to use some of my own earlier images -- such as the brushstroke -- and by changing them slightly, they become surrealist subject matter. I'm about to wind up this series, the longest of several dealing with cubism, futurism, and other styles." Lichtenstein -- Francis Meyer, Copyright (c) 1979; Picture 6, Jasper Johns

Except in his large and spectacular graphic output, Jasper Johns has floundered somewhat since his paintings of targets, flags and numbers brought him overnight fame in 1958. More than any other artist, it was Johns who launched "Pop" art. Oddly, it is also Johns who has turned out to be the most classic painterly painter in the group.

"Jasper Johns is most wonderful as a painter and is doing the best work he's ever done except for a few of the early flag, map and target paintings," says Jane Livingston. His recent Whitney retrospective affirms this. Johns, Jans Namuth Illustration 3, no caption, Johns -- "Corpse and Mirror," 1974 Illustration 4, no caption, "Diagonal With Curve III," 1978 Picture 7, Ellsworth Kelly

"Within the past three years I've been making singleshaped canvases," says Ellsworth Kelly, who was working with minimal images long before Minimal Art came along. "When you're in a room with seven of these paintings they're like seven marks on the wall, which relate both to the wall and to each other. These paintings are about shape, not about surface or strong, spectrum color. They have, I guess, a certain speed about them." Kelly, Jack Mitchell, Copyright (c) 1976