A group of 100 nurses graduated from the Walter Reed Army Institute of Nursing yesterday - the last to be trained in a program created in 1978 to help provide badly needed nurses for the Army during World War I.

With graduation of the final class, the program will be phased out by the Army because the traning has become increasingly expensive - costing nearly $15,000 per student per year - and the government has found that well-trained nurses can be recruited more economically from civilian training programs. But that is comparatively speaking only, for the military is having trouble with voluntary recruitments from civilian ranks as well.

The shut down of the program - which produced 1,000 nurses for the military - is one of the latest in a series of efforts by the U.S. armed services to combat a record shortage of military doctors and nurses, while staying within increasingly tighter budgets.

Last month, the surgeons general of the Army. Air Force and the Navy appeared before the House defense subcommittee on appropriations to plead for budget increases to pay higher physician salaries, to update military medical facilities and to provide funds for continuing education of physicians, among other things.

Lt. Gen. Charles C. Pixley. surgeon general of the Army, estimates the Army has a shortage of 500 physicians, with the most critical need for specialists in radiology, internal medicine, orthopedics and obstetrics and gynecology.

"The Army's shortage of physicians follows elimination of the draft in June 1973." Pixley said

In recent months, the three major branches of the military have been trying frantically - but without much success - to stop nurses, physicians and various members of the medical support staff from leaving civilian life and to offer increased pay and other incentives to lure skilled physicians into the armed forces.

There is shortage of 378 doctors in the Air Force, where special programs have been initiated to do such things as train nurses as midwives because obstetricians are in short supply, according to Air Force spokesman Pat Bragg.

"The biggest problem that doctors have with the Air Force is that we can't pay them enough," Bragg said. "Many of them also don't like the military environment and they would prefer not to have to move around as often as they's required to do in the Air Force."

Another problem, according to Bragg, is that recent legislation has taxed funds paid through the Health Professions Scholarship Program, one of the armed services main instruments for recruiting medical students into the military.

"As it stands now, a medical student who recieves a $13,000 annual scholarship to medical school would have to pay income taxes on that amount," said. Bragg. "This makes the idea of medical school on a military scholarship quite expensive for most students."

In his statement before the subcommittee, Vice Adm. Willard P. Arentzen, surgeon general of the Navy, noted that "availability of health services is considered to be the number two benefit by the serviceman." But he said the Navy is increasingly losing its ability to deliver.

"The all-volunteer force is definitely not working for the Navy medical department," a Navy spokesman said yesterday. "The quality of the services we can offer is not in question. But we have reached the point where we can't guarantee the avaliability of certain medical services to all of our people."

The spokesman said the Navy has a shortage of 204 physicians. He said the Navy has sought to remedy the problem by reshuffling doctors and discontinuing certain services at some sites.

Earlier this year, the Navy shut down obstetric services at six naval medical centers, according to the spokesman. Staff members from the phased-out services were reassigned to remaining centers to raise levels of service at those facilities.

The spokesman said many World War II vintages wooden buildings that had housed medical service programs have been closed because they could not meet tough health and safety standards of the federal Occupational Safety and Health Administration.

Although the shortages in medical services in the armed forces are not likely to affect care of soldiers in combat, the reductions have greatly changed the level of medical services offered to military dependents and retirees.

In past years, when a military family members neded on orthopedic surgeon or gynecologist, they went t* o the nearest medical center or hospital. Now they will have to go to some lengths to determine where the services are offered by the military or turn to a civilian physician instead.