Thousands of doctors are striking here in an effort to force the provincial government to relent in a long-running dispute over physicians' fees.

Heeding the call of the Ontario Medical Association, more than half of the 17,000 doctors in the province shut down offices on Thursday or walked away from hospital posts, according to the striking doctors and surveys by the Toronto Star newspaper.

The immediate issue in the contest with Ontario Premier David Peterson is whether the doctors will be able to bill patients as they see fit or whether they will be forced to adhere to rates set by the government.

Virtually all elective surgery has been postponed and emergency rooms are overflowing. There were no reports of patients suffering, but anger is on the rise because of the strike's inconvenience.

The Canadian Medical Association, in a gesture of sympathy, has called on doctors elsewhere to refuse to honor the Ontario government's health insurance.

Leaders of the Ontario Medical Association have made it clear that their open-ended strike is aimed not only at bringing pressure on the government but also at rousing an unsympathetic public.

"We are going to create turmoil, anger, fear, discomfort," said Dr. Edward Moran, general secretary of the association, before the strike began. "Maybe doctors don't rob gas stations because their kids aren't hungry. But their survival instincts are as strong as anybody's."

In this placid metropolis, with few stickups and an abiding faith in law and order, the doctors have emerged as a threat to peace.

Canada has one of the most extensive public insurance programs for medical and hospital care in the world. Although hospitals are privately owned and citizens may select their own doctors, medical bills are paid by tax-supported government insurance programs administered by the provinces.

Although these and other generous social programs cause Canadians to pay much higher taxes than Americans, even the most militant of doctors here join the consensus in favor of the program.

"Everybody, I think, respects the quality of health care in the United States," Moran said. "The only criticism we hear is that there are too many people who can't afford it. In Britain, everybody has complete access but mediocrity is the order of the day, and that's why, in our view, you have two-tier medicine in Britain." He was referring to the fact that, although everyone has access to state-supported medical care in Britain, those who can afford it often pay for private medical care outside the National Health Service system.

For the most part, Canada's medical system is run by the doctors, but provincial governments play an important role in setting rates. About one in 10 doctors in Ontario, most of them specialists, "extra bill" -- levy an additional charge above the government rate that patients must pay out of their own pockets.

Concerned that this practice will result in a de facto two-tier health system, with those unable to pay the extra charge receiving inferior medical care, Parliament enacted legislation two years ago to reduce federal transfer payments to those provinces where doctors "extra bill." After months of inconclusive negotiations with Ontario doctors, Peterson proposed legislation banning the practice and threatened to impose penalties of up to $7,000 on those who persist.

Protesting physicians say the most important principle involved in the conflict is whether they will be free to practice unfettered by bureaucrats.

"We're not doing this for the money; we're doing this because of the limitations on our freedom," said Dr. Heather Shapiro, as she and a group of young obstetricians attempted to rally public support before the strike began.

Surrounded by pickets proclaiming "State Medicine is a Disaster" and "We're Not for Sale," the white-jacketed physicians sat around tables on the grounds of the Ontario legislature and buttonholed passersby. They said they had made sacrifices during long years in medical school and were fearful that the Ontario government might decide eventually to follow restrictive medical licensing practices similar to those in Quebec and British Columbia, which are aimed at reducing the oversupply of physicians in the cities and channeling them into remote areas.

The obstetricians spun scenarios of being ordered to isolated mining towns in northern Ontario. The listeners often pointed out that Peterson was not proposing that.

"Nobody's listening," one of the young obstetricians remarked with quiet exasperation. "The people are not well informed."

Public opinion surveys taken by the government, newspapers and the medical association indicate a lack of public support for the doctors. A typical view was expressed by Lois Bird, a secretary who told the Toronto Star that her doctor has a sports car and a full-length fur coat. "I think he's living a very adequate life without the extra-billing, more than adequate," she said. "I think he's doing absolutely fantastic."

The physicians do not claim they face hard times. The average net income for Ontario doctors is well over $100,000. Malpractice insurance is less expensive here than in the United States. The government insurance system relieves doctors of the responsibility of chasing down patients delinquent on their bills.

Peterson's strategists acknowledge that they are depending on the public mood as well as the opposition of nurses and other health care professionals to wear the doctors down eventually. They recall how physicians relented after a similar but smaller job action here four years ago and after strikes in other provinces.

But the conflict is viewed largely as a political matchup among the advisers who seem to pay scant attention to the consequences of having demoralized doctors tending to the citizenry.