Many of Dr. D. Warren Harrison's patients suffer from chronic conditions like arthritis, diabetes and heart disease.They ''have been through things orthodox medicine has to offer. When they come to me, they are at the end of the rope,'' says the physician.

Harrison, 57, a religious man and a maverick doctor, runs a booming preventive health practice in District Heights. He is one of a new breed of health practitioners and patients who believe in a more natural approach to healing, specializing in what is called "holistic" (or wholistic) medicine.

The popularity of holistic and nontraditional medicine has been growing rapidly in the Washington area and across the nation during the past decade, despite the considerable skepticism with which the movement is viewed by the established medical community.

What patients get when they come to Harrison is an exam, questions about their state of happiness and a computerized analysis of their diet and hair to determine what vitamins, minerals and other nutrients are lacking. Harrison typically prescribes walking and diets full of grains, fresh fruits and vegetables, but low in meats and fats.

These things, Harrison says, are curative as well as good habits that will stave off further illness. He also tries to reduce patients' dependence on drugs, telling them that a healthy body often can heal itself according to the "laws of nature."

A sign on his waiting room wall reads: "Anyone caught smoking on the premises will be hung by the toenails and pommeled into unconsciousness with an organic carrot."

Harrison said he learned nutritional medicine at Loma Linda Medical School in California and from physicians he met while training in New York City, and practiced it as an Army doctor in Korea. He worked as the public health director of Uganda from 1960 until 1976, when he left to escape the political upheaval.

His demeanor is that of an old-fashioned country doctor. On Fridays he and volunteers from his Seventh Day Adventist Church are stationed in a van in a low-income housing project in the District, where they screen for childhood diseases and teach the rudiments of nutrition to local residents.

Harrison's patients are dedicated to him. Willia Roberts, 50, sought Harrison's advice after doctors advised her to undergo surgery for mouth cancer. Harrison told her to go ahead with surgery because her cancer was so advanced, but first he treated her for 10 days with "loads of vitamin C and other things from a natural source to make her strong enough for surgery," said Roberts' sister, Alfreda Williams.

Following the operation, Williams said, Harrison put her sister on a strict natural diet, vitamin supplements and laetrile. Although surgery has made it very difficult for Roberts to speak, her sister insists that she sees vast improvement in Roberts' stamina and spirit. "She is able to take care of herself and her children."

Harrison said he sends his cancer patients to specialists first, but he maintains that because cancer is a disease that affects the entire body, localized radiation, chemotherapy and surgery do not solve the problem. He gives cancer patients enzymes to "break down the wall" formed by cancerous cells, "builds immunity" with diet, vitamins and minerals, and attempts to kill cancer cells with the laetrile.

While the National Cancer Institute says laetrile, a derivative of apricot pits, is useless against cancer, Maryland law allows it to be given to patients with a prescription and special permission from the Food and Drug Administration.

In Annandale, the American Holistic Medical Association reports that its membership has doubled since the organization was formed in 1978. The association says it represents more than 500 medical doctors and osteopaths. Osteopaths are licensed medical doctors who treat illness primarily through manipulating the bones and joints.

Its members, says the association, have become advocates of treating the emotional and the physical person by using fewer drugs, and some vitamins and herbs. They believe that chronic disease can be prevented by teaching patients how to deal with stress and eat properly.

The association's president, Dr. Elmer Cranton, says physicians are turning to these nontraditional approaches because they are frustrated with writing prescriptions only to find they can "relieve symptoms but can't really ward off progression of the disease."

Dr. Arthur Furman of Brandywine describes himself as a "holistic dentist" and says his patients are referred from all types of doctors, including psychiatrists.

Furman specializes in treating temporal mandibular joint dysfunction -- disorders in the jaw and neck area that cause spasms, numbness and pain. He said he treats these problems with tryphan, a milk by-product that can be purchased at health food stores, and with mineral supplements and Vitamin C. This treatment, he says, "stimulates the brain's production of seratonin, a natural relaxer," and the muscle spasms, neck aches and teeth-gnashing during sleep stop.

"It's no great magic," Furman said. He recommends diets devoid of processed foods, white flour and sugar. "The whole approach is to get the body to heal itself. . . . Ten years ago people would have thought I was the other side of being flaky."

Dr. Nicola Tauraso, a Frederick pediatrician, has yet another approach. He teaches youngsters to relax through meditation. He promotes positive self-images through "guided imagery," in which children are taught to imagine only good things about themselves.

In addition, Tauraso prescribes a "modified macrobiotic diet" consisting primarily of brown rice, fresh fruits, vegetables and some fish. Sugar and preservative-loaded foods cause children's brains to go "crazy," Tauraso believes. Now Tauraso travels around the country giving lectures, primarily to nurses, about holistic healing and coping with stress.

"There is also a resurgence in herbal medicine; the World Health Organization has a major interest in that area," says the holistic medical association's Cranton. He believes "there are many herbal remedies that have real benefit." He notes that many common drugs come from plants, such as foxglove, from which digitalis, a major heart medication, is made.

Dr. Howard Lutz, a Washington physician, is not one to sniff at old herbal remedies. He sugggests valerian tea, which "has the odor of old socks," as a mild sedative, and senna for constipation. He sometimes prescribes garlic because it is "useful in the improvement of hypertension (high blood pressure)." He doesn't know why the pungent plant lowers blood pressure, but notes that the Chinese use a similar root to help thin the blood.

Lutz, an expert on thyroid disorders and diabetes, operates the Institute of Preventive Medicine on Wisconsin Avenue in the District, and estimates that 35 percent of his patients are from Maryland. In addition to conventional medical treatments, his patients can receive nutritional counseling, vitamins, minerals and acupuncture.

Two years ago Jeanette Swan of Spencerville was convinced by friends to go to Lutz after she developed such a bad case of hives that she said she practically lived in the bathtub and was afraid she was losing her mind. She said she went to several doctors who could find nothing wrong, but continued giving her various drugs to which she later discovered she was allergic.

Swan recalls that Lutz's tests indicated she was also allergic to a number of foods, so he put her on a strict diet. "There's very few things I can eat, but as limited as it is, it's so much better than suffering," said the 49-year-old caterer. "I lost 42 pounds and I feel like a teen-ager."

Happy patients notwithstanding, the orthodox medical community looks down on some of these nontraditional practices.

Dr. Gabe Mirkin, a Silver Spring dermatologist, sports medicine author and professor at the University of Maryland, said "The way they practice is looked down on by many members of the medical profession because (their techniques) have not been proven in well-controlled studies." Patient testimonials are often substituted for scientific proof, he said. Mirkin believes some approaches, like using laetrile to treat cancer, are harmful because they may prevent people from seeking traditional treatment.

Mirkin frowns on physicians, including Lutz, who depend heavily on vitamin therapies. "With few exceptions, there is no evidence that large doses of vitamins are good for anything other than vitamin deficiencies," Mirkin contends.

Dr. Ronald E. Gregor, a family practitioner and member of the Montgomery County Medical Society, argues that a placebo effect accounts for many successes by the nontraditional healers. "This means that 30 percent of patients will respond to whatever the approach is," he said. But Gregor believes these "cures" often can't be repeated by scientists. "If something is that good, we'd all be doing it," he said. He is concerned that patients are being "ripped off" by paying for unproven treatments.

Many of the physicians, like Lutz and Tauraso, are recent converts to a different way of doing things because of personal experiences.

Six years ago, when Lutz was 37, he developed headaches and arthritis so severe that he worked on crutches or in a wheelchair. He stopped taking medication, drastically changed his diet and discovered he was allergic to milk and sugar products.

Tauraso, like Lutz, was plagued with migraine headaches. At the urging of a relative, he took a meditation course in California. The Harvard-trained pediatrician says his headaches went away and he became skeptical of traditional medicine.

Like religious converts, these doctors speak zealously of their work. They learn by reading, talking to others like them and attending seminars.

"What I'm telling you about is not taught in the medical schools at all," said Harrison, who is frustrated with what he calls the American "disease care system" that teaches physicians to hand out drugs to treat symptoms instead of taking the time to teach patients how to get to the roots of their illnesses.