MOSCOW, Sept. 18 -- Raisa Gorbachev did not make it tonight to the first U.S. fashion show held in Moscow, but at least the clothes did. Forty-two boxes of dresses, shoes and accessories arrived Thursday, just in the nick of time, after a heart-stopping unscheduled layover between flights.

The happy ending was tonight's glittery show, greeted warmly by an elite crowd at the Congress Hall at the International Trade Center. While politicians reached agreements on arms control in Washington, de'tente here took the form of short-short hemlines, plunging necklines, puffy skirts and denim dresses -- paraded in front of a display of U.S. and Soviet flags.

The friendship theme was reinforced with a display by a group of 20 young Soviet and U.S. designers, whose work fell under the category of "design for peace." The team, sponsored by the Soviet Peace Committee, spent a week in Tbilisi, capital of the Soviet republic of Georgia, where the designers worked up ideas of bilateral fashion, such as sweaters depicting the U.S. and Soviet land masses.

The overall verdict was that the show was a major success -- not just as fashion, but as theater. Said one Soviet spectator: "It was very alive."

Raisa Gorbachev, wife of Soviet leader Mikhail Gorbachev, had been invited to attend tonight's fashion show to accept an international image award for her impact on Soviet fashion. But as it was explained to the show's organizers, she had only just returned to Moscow from vacation.

In the last two years, Raisa Gorbachev has given new visibility to the role of Soviet first lady, accompanying her husband on trips at home and abroad and taking a position on the board of the newly created Soviet cultural fund. She has also shown personal interest in promoting fashion in the Soviet Union, meeting with foreign designers and last month holding a round-table discussion with representatives of the Soviet fashion industry about how to improve the quality and availability of women's clothes here.

The American organizers of Moscow's U.S. fashion design week, which they hope will be an annual event, say they never expected the welcome they received here. (The courteous treatment did include a visit by Soviet customs officials to their hotel to inspect the 42 boxes of clothes when they were retrieved Thursday.)

Developed under the auspices of U.S. Fashion Design Week Inc., tonight's fashion show was only one part of a week-long program promoting U.S. fashions and products to Soviet buyers and producers. Manufacturers will be meeting with Soviet designers and officials, and in all, six shows will be held, for audiences totaling about 700 people.

The clothes seen here come from a range of American ready-to-wear designers, from Anne Klein and Willi Smith to Hush Puppies and Baryshnikov Bodywear (yes, produced by former Soviet dancer Mikhail Baryshnikov, now of American Ballet Theatre).

The idea came from Texas producers Michael Owen and Tommy Breslin, who saw the need to transport fashion beyond national borders. Owen Breslin Associates, which produces the annual Mary Kay cosmetics convention show and the 1986 Lulu award laser show for the Men's Fashion Association, took on the project last year after a trip to the Soviet Union.

"We recognized that the linkage between our two fashion communities offered both an exciting creative opportunity and one with strong commercial ramifications for the future," said Owen in a statement.

The commercial ramifications are indeed in the future, since none of the items shown at the fashion show can be bought in the Soviet Union now. Of the companies sponsoring the show, only one -- Wolverine World Wide, maker of Hush Puppies and other footwear -- is here to probe the idea of doing business any time soon.

Hush Puppies, making a foray into the Soviet bloc market, are due to go on Bulgarian feet in 1988, and according to Linda Water, director of marketing communications, the Soviet Union may be another market down the road. "I think it is very appropriate to see Hush Puppies in the Soviet Union," she said. "Our shoes would put them in high fashion. It would be a comfortable transition, in keeping with the life style of the Soviet population."