As psychoanalysts go, Dr. Harold I. Eist--who runs the D.C. Institute for Mental Hygiene, a psychotherapy clinic for poor people in Washington--is something of a raging bull.

He is barrel-chested, crew-cut and contentious. Trying to raise money for the clinic, he once had to be restrained from slugging a businessman who asked a question Eist thought "insulting." Until an orthopedist warned him that his bones were getting brittle, Eist arm-wrestled young male patients to show them he was a regular guy.

"The analyst is supposed to be the quiet fellow who says, 'Oh, is that so?' Harold is more like a runaway truck," says Dr. Milton Engel, also a psychoanalyst. A black colleague recently told Eist: "You're pink and big and look like a redneck."

Eist, 46, is the medical director, spiritual leader and chief cheerleader of the institute. Over the past 16 years, he has transformed it from a struggling clinic with 17 patients into a major force in mental health in Washington. The institute has three clinics in the District, more than 2,000 patients a year and a professional staff of 97. The American Psychiatric Association has rated it one of the best mental health clinics in the United States.

By training and conviction, Eist is a traditional Freudian. He spent nine years in his own five-day-a-week, lie-on-the- couch training analysis. He believes Sigmund Freud--with his conviction that infant sexuality is a key to adult mental illness--discovered "the single most useful theory" of human behavior. But unlike many of his Freudian brethren, Eist believes Freud's theories work just as well for the poor as for the middle class.

He has devoted much of his professional life to building a clinic that offers poor, seriously ill patients a brand of psychotherapy normally reserved for the well insured and well educated.

"It is an awful human wastage not to provide the disad- vantaged with adequate treatment," says Eist. Besides, he says, "I like the people. I feel a certain kinship with them."

Eist, a self-described "peasant" who says he abhors "slick" people, was born and raised in Canada. A native of Edmonton, Alberta, he spent much of his childhood playing and working in his grandfather's butcher shop there. Like all psychoanalysts, Eist believes childhood determines adult character. He believes his boyhood amid a crush of customers--poor and rich, white and Indian--in the butcher shop presaged the satisfaction he gets from running a clinic crowded with poor, sick people.

"Sometimes when I am sitting in the clinic and all those people are coming through, I think back to my childhood when all the world seemed to be working right," Eist says

After attending medical school in Alberta and studying child psychiatry at the University of Minnesota, Eist came to Washington in 1967 to work at Chestnut Lodge, a private mental hospital that is one of the few places in the world that uses the Freudian techniques of exploring the unconscious to treat patients who are extremely ill. (The patients also are often extremely wealthy. A year at Chestnut Lodge costs about $90,000.) There, Eist says, he became convinced that Freudian concepts work with the severely ill. When he was offered a chance to run a clinic in Washington that catered to such patients--who happened to be poor or near-poor--he jumped at it.

Eist, then 30 years old, was an energetic and bull-headed medical director when he took over the institute, colleagues recall.

"People don't like my missionary attitude," Eist says, interpreting himself. "I think at one time I was more obnoxious than I am now."

He can still be obnoxious, however. When Blue Cross-Blue Shield executives invited him to dinner two years ago to discuss cuts in mental health benefits, he refused to eat their food or drink their liquor. "I saw them (the executives) as unsavory and unreasonable," Eist says.

Despite his fractiousness, Eist has a reputation in Washington as a first-rate psychiatrist. He is a prolific writer of scientific papers who in the past 16 years has seen more than 4,700 clinic patients. "More than anybody in town," he claims.

He usually works from 6:50 a.m. to noon with private patients at his home in Bethesda and from 2 to 6:30 p.m. at the institute. In the evenings, Eist usually sees patients or attends meetings. As medical director of the institute, he is paid $69,400 a year. He makes about the same amount in his private practice. He sleeps four to six hours a night.

Eist finds neurotics, patients with symptoms similar to those treated by Freud, to be "kind of dull." He prefers to treat schizophrenics and "borderlines," patients who fall in a gray area between neurosis and psychosis. Unlike many psychoanalysts, Eist keeps abreast of the newest psychoactive drugs. He medicates some patients with drug dosages as large as those given by any psychiatrist in the United States.

As a past president of the Washington Psychiatric Society and past chairman of the society's confidentiality committee, Eist says public understanding of psychiatry has been circumscribed by the profession's obsessive concern for confidentiality.

Eist is protean, a slightly different doctor for each patient. He rarely affects the bland, detached neutrality of most Freudian analysts. That neutrality, he says, would confuse and infuriate sicker patients. His manner changes depending on what he thinks the patient needs. He flirts like a good-natured uncle with a woman who thinks she is "hideously ugly." He patiently instructs a schizophrenic that the voices of "god people" he hears inside his head are not real.

In an emotionally charged hour with one patient he'd been seeing for nine years, Eist bluntly criticized himself and his limitations as a psychiatrist. The patient had just complimented the psychiatrist on the accuracy of his interpretations, when Eist snapped back:

"If I'm so f-----g smart, why are you still here?"

Eist later said he made the remark on two levels: One, the patient--despite Eist's compliment--was resentful because he had been in therapy for nine years and was not cured. Two, Eist wonders why he and his profession can't cure people faster.