The big, twin-rotor U.S. Army Chinook helicopter landed in a mountain meadow next to the village cemetery, and out poured 31 American soldiers in uniform carrying M16 automatic rifles.

Rather than run in fear, however, the local peasants hurried to the rear of the aircraft and helped carry eight large metal cases up a hill to the schoolhouse.

Unlike many U.S. military training exercises in Honduras, this one had a peaceful purpose. The soldiers belonged to medical brigades that are practicing delivering health care to impoverished peasants who rarely, if ever, see a doctor. The cases were filled with medicines to be distributed free to the villagers.

For five hours here one day last month, U.S. Army physicians and medics listened to the Hondurans' health complaints, prescribed medicines or other treatment, delivered lectures on hygiene, and gave medication to nearly 600 children to fight intestinal worms. A dental unit pulled several hundred teeth, and a veterinary group gave antiparasite medicine and rabies vaccinations to dozens of horses, cows and dogs.

The medical teams fly out once or twice each week from Palmerola air field, the U.S. military command post in this country, for the exercises. The medics stress that their principal objective is to obtain field training for themselves, as some U.S. congressional critics have argued that taxpayers' dollars could be better spent delivering medical care to U.S. citizens.

"We're here to train our people. That's the main purpose. If it's stated any other way, it doesn't fit into our mission," Staff Sgt. Pete Bustamante, the noncommissioned officer in charge of the exercise here, said.

But the medics also noted that their work helps build popular support in Honduras for the U.S. military maneuvers in this country. The exercises, begun in 1982, are designed mainly to intimidate the leftist Sandinista government in neighboring Nicaragua.

The medical exercises show "that Americans are willing to help Hondurans. It instills their trust in us. Even though we're training, we're building a relationship," 1st Lt. Carey Redd, 25, of Greenbelt, Md., said. He headed a 19-person medical unit, based at Fort Meade, Md., that was in Honduras for two weeks of training.

The Hondurans here clearly were grateful for the visit, and particularly for the approximately 700 prescriptions that were passed out. The principal handout was vitamins to combat malnutrition, while the second most popular was the analgesic Motrin prescribed for muscle pain.

"We come because they have medicine. It costs 8 lempiras ($4) for a truck to go to the hospital in Santa Rosa de Copan," Santiago Cruz, a 40-year-old farmer, said. The standard wage here for a full day's work is 3 lempiras, or $1.50.

Most medicines are unavailable in this poor but well-scrubbed village nestled in an idyllic setting between two mountain streams. It has neither electricity nor telephones, and the only transportation is provided by animals and the occasional truck that braves the rocky, dirt road leading up from the lowlands.

The peasants here, like those throughout Central America, live on a diet consisting almost exclusively of corn tortillas and beans. When asked how often they eat meat, two farmers smiled shyly, shook their heads, and said in unison, "never." Domingo Chacon, 35, the male nurse stationed here by the Honduran Health Ministry, is the only medical worker for 1,500 persons in the district. He seemed to be well trained, but he complained that the only medicines that he had available were penicillin and aspirin.

"Even though we identify the disease, there isn't the medicine to cure it," Chacon said. Referring to the last U.S. medical exercise here, 11 months ago, he said: "There are many people whose ailments have been cured by the treatment that the gringos have brought."

One of these was Maria Consuelo, 37, who said the medicine provided last time for her skin ulcers had saved her life. Unfortunately, it did not clear up the problem permanently, and both Chacon and the U.S. medics said the visits are not held often enough to sustain a long-lasting improvement in the villagers' health.

"We're just scratching the surface," Bustamante said.

As a result, the medics view the lecture on hygiene and preventive medicine as their most important single contribution. They carefully channeled the peasants through a series of stops to make sure that the talk was heard. First the villagers saw a doctor in the schoolhouse and received a prescription for medicine, then they heard the lecture and finally the portable pharmacy filled the prescriptions.

"We basically use the pharmacy as bait. That way we ensure that we are doing something educational as well as medical," 1st Lt. Robert Fisher, the chief pharmacist, said. He is based at Ft. Meade's Kimbrough Army Hospital, and is in Honduras for six months of training.

The hygiene lecture, delivered in fluent Spanish, stressed the importance of washing hands before preparing food and of boiling water to kill parasites. But health worker Chacon said he delivers talks on hygiene every day at his clinic, and the villagers pay little attention because they are set in their ways.

"People say that the more you brush your teeth, the more cavities it causes. There is a belief that boiling water causes it to lose its strength," Chacon said.

The U.S. medics were enthusiastic about the training benefits of the exercise, and they appeared to be receiving a valuable crash course in the difficulties of practicing medicine in a poor country.

Maj. Melvin Cohen, an Army doctor based at Brooke Army Medical Center in San Antonio, Tex., was on his first exercise of this sort, and he confessed afterward that he felt overwhelmed.

"It's completely unlike any other experience I've had as a physician. A lot of people said they just hurt all over. It could be one of 150 diseases, and when you've got to see 300 patients in five hours, you don't have time to narrow it down. It's hard to have the knowledge and not be able to use it," he said.