The 2,700 guests at Saturday's sellout Congressional Black Caucus Luncheon at the Washington Hilton had already tuned in (and spent money on) the best of the fashion trends for fall before the fashion show began, and turned out to be the spiffiest fashion show audience this town has seen in eons.

As the rock music blasted across the hugh International Ballroom and the 38 models made their way down the long T-shaped runway (up to their ankles in "clouds" of dry ice), the audience clapped and cheered its approval not only for the clothes but for the models, many of whom they recognized as familiar faces in ads and commercials.

The theme of the show was color, and the winning colors were clearly white and black. The white segment opened with suits swathed in white mink scarves and peaked with a Tracy Mill white sequined evening dress whose deep side slit was no more revealing than the totally see-through dress itself. Black clothes included men in macho black leather suits (over nothing), black leather fringed jackets and finally dramatic black silk gowns and tuxedos. The feather-printed furs from Ripa were show-stoppers.

It was the first time Johnson Products, leading maker of black hair care and beauty aids, put on the Black Caucus luncheon fashion show. "It seemed like an opportunity for us to get a lot of savvy, fashion-conscious ladies familiar with our products," said George Johnson, president of the $35-million business. "A lot of women don't know we make cosmetics. And you can't show off clothes unless the hair and cosmetics are right."

For many of the guests, the luncheon was one of the season's important dress-up occasions. "I dress because I know everyone else will dress up," suggested Anne Jensen, administrative aide at IBM, who was wearing a gray belted suit. Her friend Sylvia Patterson, who also works for IBM, admitted she had "looked for a year to find the right dress for the luncheon." She found it -- a pleated chemise style by Albert Nipon. Betty Johnson, a party consultant from Bethesda, said the white knee pants she wore "were resurrected from years ago."

Television news commentator Lark McCarthy told the crowd she gets as many comments about what she wears as what she says on the evening news. "I once got a three-page, handwritten letter from a viewer criticizing my nail polish," she said. "Hopefully I'll find in this fashion show an outfit which will take me to a fire in the morning, the field in the afternoon, Capitol Hill in the evening and still be right for television at night."

Luncheon guests were served a scaled-down version of the hotel's current luncheon special, stuffed chicken breast, which was on the menu at the Salvation Army fashion show luncheon in the same room the day before. The youngest guest Saturday was Marion Christopher Barry, 3-month-old son of the Mayor and Effi Barry. The baby seemed unfazed by the large, noisy event, having attended a soccer game last weekend.