Tamara N. Kerim is an old hand at East-West trade. And she has a word of advice for U.S. companies trying to do business with the Soviet Union: perestroika.

Perestroika, the policy of system restructuring that Mikhail Gorbachev is pursuing in tandem with glasnost (openness), should also apply to U.S. companies, says Kerim. "It's no longer business as usual in Moscow. We must have a perestroika of our own."

Kerim, a Russian-born American, is president of Intertorg Inc., one of the dozen or more U.S. trading companies that arrange deals between the Soviets and American corporations.

Intertorg has a staff of seven in Moscow, while Kerim and three associates operate from California. Kerim said commissions in an average year amount to about $1 million.

In the centrally planned Soviet economy, deals have traditionally been handled exclusively by the Ministry of Foreign Trade in Moscow. But recently, under the new Soviet policy, the state authorized some 70 major enterprises to directly import and export and to negotiate joint ventures with foreigners.

For the first time, Soviet managers are having to concern themselves with the bottom line. Thus, Kerim believes they now will be more careful with how they spend their money.

In this new world, Kerim says it will be up to U.S. companies to adopt a more creative approach toward the Soviets and "show them how we can both make money," she said.

Last July, Intertorg, a private U.S. company based in Sacramento, Calif., signed a three-year agreement in Moscow with Licensintorg, the state-owned trading organization, for just such a deal: the manufacture and marketing of Soviet fashions in the United States. It is the first consumer venture of its kind between the two countries, according to Kerim.

Because it involves Moscow's top designer, Viyacheslav (Slava) Zaitsev -- the maker of some of the eye-catching outfits Raisa Gorbachev has worn on foreign trips -- the announcement has attracted more popular interest than some bigger industrial deals with the Soviet Union.

The designer will make his debut later this month at a $250,000 fashion show of his originals at the Starlight Roof of the Waldorf Astoria in New York. Since high duties on Soviet clothes make importing too costly, they will be made in the United States with American fabric.

Buyers will be invited to place orders with Tanner Companies Inc., a Rutherfordton, N.C., apparel manufacturer. President James T. Tanner said he has contracted for a maximum of 30 styles per season, or approximately 6,000 garments. At $125-$150 wholesale per outfit, Tanner projects that the first year's sales could amount to between $750,000 and $1 million.

"We've made a couple of samples already," said Tanner. "The patterns are crude; they must be modified before they can be made up. But the Soviets had the right American sizes. The styles are quite nice; they look like Paris to me," he added.

The clothes will be marketed by the House of Zaitsev in San Francisco, a creation of Intertorg, which is financing the venture. Private American investors are a possibility later if the venture catches on, said Kerim.

Zaitsev, who reportedly earns the equivalent of $375 a month for his work at Moscow's Dom Modi -- or about the price of one of his evening dresses there -- will receive a license fee for his designs. He will also receive royalties from sales of the clothes.

This unorthodox arrangement was cooked up one cold day last January when Kerim and Suzanne B. Stafford sat in the sauna of Moscow's Mezhdunarodnaya Hotel after attending a Zaitsev show. The women -- who are, ironically, too petite to wear the Zaitsev clothes made for Russians -- thought American professional women would like the elegant styles. Neither woman had any fashion experience, apart from an unsuccessful attempt by Stafford to import Russian sweaters.

However, both women do have extensive experience with U.S.-Soviet trade. Stafford, 39, of Colfax, N.C., served as director of countertrade in the international trade division of BankAmerica until 1984. She became well acquainted with Kerim only a month before the sauna session, but she knew of Kerim's reputation in East-West trade.

Kerim, 50, was born in Odessa in southern Russia. During World War II, she and her parents fled from the advancing armies and wound up in a concentration camp in Graz, Austria. The family came to the United States in 1948.