Red toenail polish.

You know she is wearing red toenail polish because she's also wearing highheel sandals. And we're not talking about some lightweight: This is a United States congresswoman. Not only that, congresswomen have been seen in bright print dresses, silky pastel blouses, slit skirts and clinging sweaters.

It's enough to drive John T. Molloy into a polyester straitjacket.

Molloy has packaged his secrets to success with his bestsellers, "Dress for Success," "The Woman's Dress for Success Book" and a syndicated newspaper column. Follow his simple guidelines and you, too, will be able to make your clothes, as he puts it, "a tool and a weapon, particularly in enabling one to get ahead."

For women, as he sees it, this means suits in blue, gray and beige, a simple contrasting blouse, and plain pumps with closed toe and heel. It also means no prints, no bright colors, no pastels, no sweaters, no pocketbooks, no skin, no obvious perfume and no toenail polish -- or at least no shoes that let you see toenail polish.

How do some of Washington's successful women view Molloy's dictums? Positively and negatively, it turns out. But whether or not they agree with his views, almost everyone seems to have heard of Molloy. And some women will admit Molloy's opinions -- whether or not they follow them -- have slipped into their subconscious.

"Molloy gives you all the safe things," says Rep. Geraldine Ferraro (D-N.Y.), "but as a woman develops her own style, she can deviate from that standard.

"I would never recommend adopting a uniform. A woman's individuality is expressed in how she dresses."

When interviewed Ferraro was wearing a short-sleeved turquoise blouson dress, open-toe high heels, and carrying a purse, thus violating at least three of Molloy's rules. She also looked professional and comfortable.

The wardrobe of Susan Estrich, 26, the first woman president of the Harvard Law Review, and for the past year, a law clerk to U.S. Supreme Court Associate Justice John Paul Stevens, could make Molloy give it all up and wear salmon leisure suits.

"I wore jeans every day," she says. "Justice Stevens told me at the beginning of the year to wear whatever was most comfortable. And when you're working hard, it can be easier if you're comfortable."

Estrich says she doesn't even own Molloy's prescribed outfit, but has never had trouble proving her competence. "My boss took me just as seriously in jeans as a suit."

While she admits the informality allowed her by Justice Stevens is not the norm -- and she may change her wardrobe for her new job as an assistant

"The people I meet know I'm an I.a. I don't have to spend time getting "expect to buy a dark suit, low-heeled pumps and live happily ever after.

"Clothes can be fun. That doesn't sound like much fun."

Gwen King, 38, legislative assistant to Sen. John Heinz (R-Pa.), says her wardrobe "is so wonderfully limited, that I never have a difficult choice about whether something is appropriate or not."

King says she favors skirts and blouses, most of which her husband buys as birthday and Christmas gifts.

"The people I meet know I'm an La. I don't have to spend time getting over that hump," she says. "A lot of the people I come into contact with are women. I don't even notice what they're wearing."

King also observes that a woman can use Molloy's book as "her bible," but that won't help if she doesn't do her job well.

"I don't think Sen. Heinz cares what we wear," she says, "just as long as we're clad. What counts is what I can tell him about my legislative area uhen we sit down and talk."

At least one Washington career woman finds she is taken seriously in a sundress.

"I never get a different response from the people I interview if I'm in a sundress or a suit," comments Rahcelle Patterson, a reporter with the Washington bureau of The Boston Globe. She was wearing a blue and white sundress, happily violating one of Molloy's rules for professional women: "Make sure you don't dress like a secretary."

"I don't care what people on the street think I do on the basis of what I wear," says Patterson, who is in her 30s.

"You don't have to wear a drab suit in order to be taken seriously. And in my business I have to be taken seriously."

She adds, though, that she has altered her outfit to suit a story.

"I had to go to the Iranian Embassy right after the takeover. I was wearing a sundress with slits. I was apprehensive that they'd throw me out because of my outfit, so I put on a jacket."

In spite of all this sartorial informality on the part of successful women, there is agreement that for anyone going into a very conservative corporate field -- such as banking or engineering -- conservative dress, for both men and women, is the norm.

Anita Fishkin, president of Fishkin & Associates, which matches executives and corporations, has a cautionary tale.

"I sent a very attractive, competent woman to an engineering firm for an interview. The vice president of the firm called me to say the woman was dressed for dinner and dancing.

"When I spoke to the woman she said, 'Do you know how much money I spent on those silk pants?' I said, 'I don't care if you spent $500, the outfit bombed.'"

But Fishkin also thinks Molloy is too extreme: "A woman has to have a sense of herself . . . He takes away the individuality a woman can show in dress and make-up."

Perhaps the hardest line on women's work wardrobes came from Washington dress consultant Nancy Thompson.

"Women should stop looking sexy one day, attractive the next, professional the third," she says. "They should look professional all the time, and that means putting on a jacket.

"When you go into an office staffed with women, you can't tell the managers from the secretaries. If women want to be taken seriously as professionals, they are going to have to start dressing for the part.

"One of the problems," says Thompson, "is that there haven't been enough role models for women. Margaret Thatcher -- whatever you think of her politics -- dressed for the job she was going after. She wears suits often. Anne Armstrong will probably be nominated for vice president some day -- she just looks like a vice president."

Thompson agrees with Malloy about jackets and always skirts -- not necessarily suits -- but says she would like to see more variety in color

She adds, however, "Men use the business suit to identify each other. Until men at the top start giving up suits, professional women should wear them too."

"It just isn't realistic to think that women are free to wear whatever they want now," says Catherine Hartnett, 27, of the Democratic Studies Group and a recent candidate for vice chair of the National Women's Political Caucus.

"As a feminist, I'm not uncomfortable with dressing to get as much power and money as you can.

"But of course, I'll use that power differently than men."