Jeane Kirkpatrick says she cares a lot about clothes. The first woman to serve as U.S. ambassador to the United Nations buys from such substantial designers as Harve' Benard, Joseph Picone and Albert Nipon. She shops when she can on trips, ordering clothes made in the material, color and cut she prefers, or buying them off the peg in size 12. With the lengthy lunches and dinners of diplomatic life, her size "is on the verge," she says with a laugh.

Kirkpatrick takes great care each day, she says, to wear clothes that fit her activities, trying also to avoid wearing the same thing on consecutive days. "It makes a difference," she says. "Not a great difference, but I am conscious of it."

The former Georgetown University government professor feels bruised by the mention in People magazine three months ago that called her "dowdy even for an academic" and quoted "Language of Clothes" author Alison Lurie, who labeled Kirkpatrick's style as "bunchy, rumpled. It looks like she found her clothes at a rummage sale."

Says Kirkpatrick: "I don't know what provoked them. It bothered me. It was an assault of a sort. Totally unjustified."

Kirkpatrick is more than ready to defend herself against the unjustified comments. She thinks she does the best she can in her hectic, two-city life, where daytime and evening activities often meld.

What may have prompted People's cutting remarks is Kirkpatrick's chronically haphazard appearance on the shuttle between New York and Washington, a round trip she makes as often as four times a week. Usually, she boards planes juggling several stuffed file folders, a book, notebooks and bag. The similar appearance of disarray by another former academic, Sen. Daniel Patrick Moynihan (D-N.Y.), is considered part of his charm. But with Kirkpatrick, the expectation is different. And she finds matching clothes and accessories a challenge.

At her State Department office last week, she was wearing a deep rust suede suit she had had made-to-order in Colombia and a collarless pale silk blouse from Thailand. She had risen early that day, washed and set her hair as she does daily, and decided on this outfit after checking her schedule, which included briefings at the State Department, lunch at Jean Louis and cocktails at Blair House. What she hadn't counted on was that she left the shoes she likes to wear with the outfit in New York the day before.

"I can't let it stop me. How could it? I can't stay home because I don't have the right shoes," she says. "I thought about not wearing the suit because I didn't have the shoes and I thought about choosing something to go with the shoes in place of the suit. But I decided I really wanted to wear the suit."

Two wardrobes, one for each city, might solve her problems, but that's out of the question, she says. "In fact, I can hardly afford one, clothes are so expensive."

Kirkpatrick's most difficult wardrobe problem is the transition from day to evening. She says: "How do you make a transition when there is no time for transition?"

The U.S. ambassador to the United Nations spends most of her time in New York, particularly during General Assembly sessions. This causes problems with her Washington wardrobe, she says. "I have a way of underestimating on a chronic basis how many evening clothes I need in Washington."

She is resigned to the fact that "what I need is never wholly in New York or Washington or where I need it."

If living and working in New York and Washington is a major problem for Kirkpatrick, so is her in-town schedule -- many daytime activities conclude with work-related social activities. She works in a world that is almost totally male, yet the male formula of standard suit or black tie doesn't apply for her. It's hardly a head-turning development if a man slides from the office to a black-tie function wearing a business suit.

Kirkpatrick points out that when President Reagan appointed her to her post, she became the first woman assigned to represent a Western nation. And even the Soviet Union has not had a woman representative at the United Nations, she adds. "I live in a circumstance where there are almost no women, either in Washington or New York or almost anyplace I go, except socially in the evening."

Suits are her "protective coloring," she says. "I feel it is expected. It is businesslike to wear a suit, like a man." She owns several pin-striped suits. For evening, though, she always wears dresses.

She has never refused to attend a function because she didn't have time to change, but wonders if her decision was always right. "It may be that going inappropriately dressed was the wrong decision," she says, referring to two or three recent occasions when she was tied up until 9 or 9:30 p.m. "It may have been better for me to say 'Sorry, I can't make it.' It may have been offensive to some of my friends."

Kirkpatrick also is uncomfortable wearing the same clothes too frequently. "I can't afford to always wear something different," she says, but one afternoon last week she realized she would have to wear the same long dress that evening that she had worn the night before. That bothered her. But there were only one or two persons present that evening who might have known. "I don't know if they noticed; I certainly didn't ask them," she says. She thought about it early in the evening and once again later, she says, but forgot about it at the party.

Everything she selects is made from natural fibers. "I feel strongly about textures, about clothes that feel good, like silk and cashmere and suede," she says. "I know suede is fashionable this year, but my liking for suede is not an artifact of this year's fashion, just an artifact of the fact that I like suede for the way it feels and the way it looks."

In warm weather she chooses silks and cottons because they feel good. "I don't know if that is decadently sensual, but it is important to me to have clothes that feel good as well as clothes that I think look good. I can't bear clothes that feel scratchy. That is the biggest reason for preferring silk or cashmere or lambswool. "Acrylic feels like it has electricity in it. Polyesters don't feel like cotton and don't look like it."

Occasionally there are mistakes when she has her clothes made, Kirkpatrick says. "I just push them to the back of the closet and they are just wasted," she admits. But when a style works well, like her collarless blouse, she may order the same style in several colors.

Kirkpatrick grew up "caring not much, but some" about clothes, attaching her style more to the bluestocking tradition of Barnard College than the feminine style of Stephens College in Columbia, Mo., where she first attended college. Her choice of designers now, she says, is no different from when she was a Georgetown professor.

She is amused by one of her sons, who once claimed she looked like "a bag lady" on the shuttle with all her papers. "I've read those articles from time to time about what the well-organized executive woman has to keep well-organized with organizing purses, briefcases and bags. I carry lots. I never have a briefcase big enough for all the papers I have to carry."

Six months after Kirkpatrick's appointment to the United Nations, Belgium appointed a woman, Edmonde Dever, as its representative. Last week Kirkpatrick invited Dever, whom she describes as "quite a stylish woman," to a dinner she hosted for Defense Secretary Caspar W. Weinberger and his wife, Jane. "She Dever found herself in a situation where, for a compelling reason, she could not change from daytime to evening clothes. She was in a tailored, daytime suit for a fancy evening party. She was uncomfortable, she told me, and she explained to Jane Weinberger, as well. I kept saying, 'It doesn't matter, you look lovely.'

"She felt uncomfortable and I know exactly how she felt."