One of every five doctors serving in the U.S. armed forces does not have a medical license, according to officials of the Pentagon's Office of Health Affairs, who say Defense Secretary Caspar W. Weinberger will be asked next month to order all 13,000 active duty doctors to obtain licenses.

In figures supplied to Rep. Ron Wyden (D-Ore.), who has sponsored an amendment to require licenses for all doctors in the military health care system, the Pentagon said 27 percent of Navy doctors, 25 percent of Army doctors and 11 percent of Air Force active duty doctors are not licensed.

"Not holding a license does not mean you are incompetent," said Julian Barber, a special assistant in the Office of Health Affairs. "It's really a problem of perception. Parents ask, 'What is the military doing letting an unlicensed doctor work on my son or daughter?' "

Wyden said that of the 12,893 military doctors on active duty, 2,774, or about 21 percent, do not hold licenses.

The Pentagon does not require doctors to hold medical licenses, and many doctors enter the military directly from medical school. Under that arrangement, the doctors are not required to take either of the national medical qualifying exams that nonmilitary doctors must pass before they are issued a license by a state medical board.

"The licensing exams test for clinical competency, something that just graduating from a medical school doesn't assure," said Dr. John C. Sage of Omaha, president of the National Federation of State Medical Boards.

Some doctors who joined the military during their careers let their civilian licenses lapse. But a mass screening of military doctors by the American Medical Association's discipline bank shows that a small number of military doctors joined after they lost a state license for disciplinary reasons.

Preliminary results of the AMA screening showed there were 29 Army and Air Force doctors whose licenses to practice were revoked or suspended. The Navy's figures have not been made public, said Capt. Edgar Blount, a doctor and special assistant for medical affairs.

Wyden and Pentagon officials say that requiring military doctors to meet civilian standards will improve the quality of military medicine.

As a result of media disclosures and internal audits that show that the military has poorly monitored the quality of its doctors, the Pentagon ordered all branches of the military in February to collect and check all medical degrees and other credentials for all new applicants.

"There are cases that have received a great deal of attention in the media that would not have happened if this . . . had been in place," said Barber. "At one time, there were those who made accusations that the military was a dumping ground for incompetents. That cannot happen [now]."