Everybody must have know the Russians were coming to the Renwick Gallery last night, because it looked like everybody in town followed them there.

That meant 1,500 people -- some waiting as long as 45 minutes outside -- ascended the marble steps toward the galleries to dring vodka and preview "The Art of Russia: 1800-1850 exhibit.

The hosts of the show, which opens today, were overwhelmed by the turnout.

"Rather staggering, isn't it?" said Dorothy Fisher of the National Collection of Fine Arts. "We only expected 700."

Forty minutes after the doors opened. Gallery Director Lloyd Herman politely asked people to move on once they had seen the art and socialized. Ten minutes later the Stolichnaya vodka ran out.

"I don't believe it," said a harried bartender. "White wine is all we have."

Meanwhile, Joshua Taylor, director of the National Collection, played host to the guests waiting in line outside under threatening skies.

"It is a problem' said the apologetic Taylor. "You can only get so many people in the gallery at one time."

What possessed so many people to face August humidity and crowds for Russian art?

Everybody had a different theory.

"It's just damned good," said Harry Lowe, assistant director of the National Collection.

"It could be that it's August and there's nothing else to do," said Nora Panzer, docent coordinator of the National Collection.

"Me? I'll do anything to support the SALT treaty," said Sam Ramar, a Russian historian.

"The invitation said the Ambassador of the Soviet Union and I said 'Wow, this is hot stuff," said Stephen Kesselman, 21, a law student at American University.

Unfortunately for Kesselman, Soviet Ambassador Anatoliy F. Dobrynin was still vacationing on the Caucasian side of the Black Sea. In his place were Deputy Ambassador Vladillen M. Vasev and voriety of other Soviet Embassy officials.

"I never saw so many people at an American museum," said one of several Russian museum officials there.

Joseph Hirshhorn, tan and recently slipped inconspicuously through the exhibit. The Hirshhorn Museum foundler's verdict: "It's very beautiful, but some are very sensitive paintings and some are not.'

Others had a hard time telling the American art from the Russian. Surrounded by the 19th-century American works that hung in the reception room, Kennan Institute Director Fred Starr had to tell several people they weren't looking at the Russian exhibit.

'It's striking to note how many people come in the reception room and think this is the exhibit," said Starr. "But there are a lot of similarities in the paintings of the same time period."

"It's super, really incredible," said Barbara Shissler, the woman responsible for initiating the project. Shissler is a former director of the University of Minnesota Art Gallery, where the exhibit first opened.

"When one does it in Minnesota," Shissler continued, "one wonders how it will be received in Washington."

An admirer piped up: "Looks like it's being overreceived." CAPTION: Picture, The line outside the Renwick, by James A. Parcell -- The Washington Post