The chiefs of most medical services at Washington's giant Group Health Association are resigning their administrative jobs to protest a refusal to let its doctors incorporate as independent practitioners instead of continuing as GHA employees.

Their spokesman, Dr. Daniel Patterson, stressed yesterday that the 12 chiefs -- including the medical director and heads of services like obstetrics and psychiatry -- are quitting only administrative posts and are not leaving GHA as doctors.

"But many of our physicians have told me that if we can't agree within a reasonable or even short period, they'll be leaving entirely," Patterson said.

"Group Health hasn't had a medical director for the last week," said resigned medical director Dr. Donald Mitchell. "There's no one to do doctors' scheduling or assure night, weekend and holiday coverage, and the work of the quality-of-care and other committees is suspended."

Louis J. Segadelli, GHA executive director, said yesterday he does not know how he will fill all the administrative posts since he has not received all the resignations.

Patterson -- until yesterday chief of psychiatry at GHA -- heads the "GHA Medical Group," the corporation formed by 52 of Group Health's 66 staff doctors.

They have been trying for more than a year to persuade Group Health's board of trustees to let them leave the payroll and negotiate with GHA as an independent practitioners' group.

Yesterday's decision by the service chiefs to quit their administrative duties was prompted by an annual election this month in which GHA members chose three new directors opposed to the doctors' corporation and defeated another slate willing to deal with the corporation.

Group Health is one of the nation's oldest, largest prepaid health plans, offering members virtually all medical and hospital care. Its headquarters are at 2121 Pennsylvania Ave. NW with branches in Maryland and Virginia.

Rising health costs caused it to raise premiums sharply in 1975 and 1976 and to lesser extent this year. Fullest coverage now costs a family $109.06 a month (or $51.96 every two weeks for federal employees).

Last year, the plan lost some 16,000 members, in contrast to a usual loss of 5,000 to 7,000 a year, though it enrolled 16,000 new ones to keep total membership at 102,000.

"The membership loss is due to fees that are too high because of inefficiencies," Patterson said. "Also, there was a physician turnover of 11 per cent last year. We feel we can work better and give better, more efficient care if we are equals."

Money, he and Mitchell maintained, is not an issue. Group Health doctors are paid $32,000 to $68,-000 a year, Mitchell said.

The doctors' opponents -- directors who won the membership vote -- argue GHA originated as a program controlled by consumers, and services to consumers will suffer if doctors take full control.

Segadelli, GHA's executive director, has supposed the doctors, arguing that plans like the West Coast's big Kaiser clinics and Group Health Association of Puget Sound have dealt successfully with their doctors as independent practitioners.

Other service chiefs who have resigned or were sending in resignations, Patterson said, are Dorothy Million, internal medicine; James Izanec, obstetrics-gynecology; William Ibrahim, ophthalmology; Morris Osborn, neurology; alan Lesselroth, radiology; Salman Kazmi, urology, and heads of four suburban clinics: George Keeler, Rockville; Charles Schilling, Annandale, and Harvey Gold and Raymond Turner, Prince George's.