Physicians responsible for the care of more than 100,000 Washington-area residents went on strike yesterday morning, setting up a picket line after contract negotiations between their union and the Group Health Association broke down.

The strike by the 55 physician members of the Group Health Association Physicians Association appears to be the first by doctors belonging to a union certified by the National Labor Relations Board. An official of the American Medical Association said yesterday that the strike was the first of its kind, but "It's not going to be the last one of these things to happen. I think there'll be others."

The strike was voted by the Physicians at a Friday night meeting after they rejected, 38 to 2, GHA's final contract offer. Negotiators for the union and GHA immediately went into a marathon bargaining session with the aid of a federal mediator. The session broke off after 3 a.m. Saturday when it became clear that an agreement could not be reached.

Union physicians said they would continue to treat their patients who were hospitalized and would continue to take their turn seeing emergency patients.

GHA canceled all routine appointments scheduled for yesterday, which is normally a light day, and closed all of its clinics except the main facility at 2121 Pennsylvania Ave. NW. An emergency clinic there was staffed with some of the 20 or so supervisory physicians who are not striking.

Physicians, carrying professionally-prepared signs saying "Doctors on Strike," walked a picket line outside the Pennsylvania Avenue facility. Registered nurses and other GHA employes who belong to unions of their own, honored the doctors' picket line, according to both the physicians and GHA officials.

GHA is the Washington area's largest prepaid group health plan, with about 109,000 members. The union has been trying to negotiate their first contract with GHA since the physicians first formed the union last January. A federal mediator was asked to join the negotiations in March when they bogged down.

GHA had offered, and the union's negotiating team had accepted, a salary package calling for average pay for physicians to go from the present $53,000 a year to $60,000 this year and $66,000 in 1979. Starting salary for internists and pediatricians would go from $36,500 to $38,500 immediately and to $40,810 in 1979. The highest paid group of physicians, obstetrician-gynecologists with eight or more years' service, would go from $71,500 to $80,000 in 1979.

Items separating the physicians and GHA include the adequacy of mal-practice insurance for the physicians under a self-insurance scheme GHA wants to adopt, continuation of a ban on GHA physicians' being employed outside the plan and changing the number of clinic hours for internists and pediatricians.

According to negotiators for both sides, the marathon session Friday night and early Saturday morning not only failed to narrow differences but may have also increased friction between the two sides. As a result no talks were scheduled yesterday or Sunday.

Harold Wool, president of GHA, said it had been "impossible" to settle differences Friday night because the doctors had presented no concrete proposals, but rather a "long shopping list" of demands. "They had obviously made up their minds that they were going to strike (Friday) evening no matter what," Wool said. "I think it's very regrettable."

For their part, the physicians generally spoke of GHA officials in the same terms that have become so familiar in union strike situations, referring to them as "management" and using epithets to characterize the terms GHA offered.

GHA is oen of the oldest prepaid group health plans in the country, formed 40 years ago. Its governing board of trustees is elected by its members. Unlike commercial health insurance plans, GHA not only collects a premium from its members, but also supplies them with necessary medical and hospital care rather than having the members seek care from private, fee-for-service physicians. GHA's physicians are salaried employes of the plan and do not receive fees beyond the salary for their services.

Friction between GHA's physicians and the board has been growing since last spring when the board rejected a proposal by the physicians to form a separate corporation to contract with GHA for their services.

Three weeks ago as the negotiations were going on, several physicians who were members of the union said in interviews that they could not support a strike of physicians. In the end, however, some of the same physicians interviewed voted to strike Friday night and were walking a picket line Saturday.

The few patients who showed up a GHA yesterday seemed disturbed about the strike but not upset. One man, who declined to give his name, said of the physicians, "It's a matter of their own conscience. I'm sure they're concerned about their patients." He said, however, that he would have prefered the matter to be resolved by arbitration than a strike.