PARIS -- Universal medical coverage for all residents exists in every industrialized nation except the United States and South Africa. But each system is different. The care under these national plans is not always free, and doctors may be in private practice.

The U.S. is a mecca of medical technology with its mechanical hearts and neonatal intensive care units. But it doesn't have a national health plan. Should it?

What follows are reports from France, Canada and Japan.

France's health care system, long regarded as among the best and most liberal in the world, has entered a profound financial crisis that has led some experts to warn of bankruptcy.

The difficulties, according to government officials and health experts, grew mainly from the rising costs of improved medical services without corresponding rises in Frenchmen's contributions to a government-run health insurance they have cherished since the end of World War II.

The unfavorable equation has been thrown further off balance by persistent unemployment of more than 10 percent of the work force, they say. This means fewer Frenchmen have social security contributions deducted from their paychecks to finance their own health care or that of their often elderly and chronically ill relatives.

The social affairs and employment minister, Philippe Seguin, pointed out recently that medical improvements in the past several years have prolonged the lives of these relatives considerably, but often at the cost of hospitalization and use of expensive machinery. Forty percent of France's $6.6 billion social security deficit can be accounted for by the cost of caring for elderly long-term patients who only a few years ago would not be able to live, he said.

In a turn to morbid humor, some officials in Seguin's ministry calculated they could eliminate the deficit entirely by hiring assassins to visit hospitals and murder old people seven days before their deaths.

"If the rate of health expenses continues to rise the way it has in the last five or 10 years, the entire gross national product would go for medicine," Seguin said at a lunch with reporters. "This is absurd, of course. But it gives you an idea of the scope of the problem we face."

Under the French system, government health insurance covers all residents of the country and pays for most hospital care and visits to doctors' offices. The national plan is funded by social security contributions, which are deducted from people's paychecks. Fees are set by the government. At the same time, most physicians are in private practice and are allowed to charge patients more than the set fee. Patients in turn can choose their physician.

As things now stand, ministry officials calculate that France's overall social welfare spending, including unemployment compensation and old-age insurance, has grown to nearly a third of the gross domestic product. About a third of that, they say, is spent on health care.

The problem is that the health part of these expenditures is growing rapidly and with no slowdown in sight. The social security system paid out 11 percent more for medical insurance reimbursements alone in 1986 than in 1985, a real increase of 4.6 percent, according to calculations adjusted for inflation and other factors.

"The bill for medical progress in our system makes things so that we almost have a built-in deficit," Seguin complained.

Frenchmen have become so used to their national health insurance system and other social security measures that cutting back on benefits is almost a political impossibility.

In an effort to economize, for example, Seguin recently eliminated "comfort" drugs such as sleeping pills from the social security reimbursement list. His move provoked an immediate outcry from the Socialist opposition and a spate of television interviews with elderly patients who said they needed the medicine daily but could not afford to keep paying for it out of their own pockets.

Similarly, Seguin for the first time ordered patients sending off for medical reimbursements to put a stamp on the envelope. Previously, mail to the social security system moved free.

Frenchmen had become so used to this privilege that the ministry had to pay for television advertisements to persuade them to stamp their reimbursement forms before dropping them in the mailbox.

Anne Guesdon, a spokeswoman on health affairs at Seguin's ministry, said officials there operate on the premise that medical insurance and other social security benefits cannot be reduced substantially. Frenchmen in the last 40 years have come to think of their social welfare system as an untouchable part of government responsibility, she said.

As a result, in spite of calls for greater efficiency and economy, most attention has focused on ways to raise more revenue. Seguin and other officials have evoked possibilities such as increased paycheck contributions or a special tax rise earmarked for social security.

These solutions also carry a heavy political price, however. Seguin has organized a national forum -- les etats generaux de la securite sociale unitals -- to cushion the political blow by stimulating citizen awareness of the need to do something swiftly to reduce the deficit.

The health ministry produced a series of posters and television advertisements, using a giant whale as its symbol, to attract public attention to the consultation. Guesdon said the whale was chosen not, as some Frenchmen have suggested, because social security risks extinction but because it is considered an animal without enemies but that needs help.

A "committee of wise men" appointed to organize the forum underlined French attachment to the system and said in a report that all groups concerned agree that "appropriate measures be taken in time to prevent {social security} from falling into a state of halting payments."

The committee, in preliminary suggestions, urged a stiff rise in taxes on alcoholic beverages and tobacco as a first step and said some type of temporary income tax should be imposed to make sure the system itself does not become mortally poisoned by its generosity.

But generosity -- the fact that everyone in France has access to care without personal financial hardship -- is what national health insurance is all about. A middle-aged woman in Paris who noticed a lump in her breast in 1981 found out just how generous the French system really is.

After a diagnosis by her personal doctor, she was hospitalized for 15 days during which a cancerous tumor was removed. The entire bill, she said, was paid for by the government health insurance plan, which is run by the social security administration.

For months afterward, she received radio therapy and then chemical therapy, all paid for by the insurance. Her regular checkups also were paid for until the insurance administration, consulting with the doctor, determined last year they were no longer necessary as part of the treatment.

Another woman who felt a high fever called a private ambulance service. She was picked up at home, she recalled, transported to the hospital of her choice and admitted for examinations immediately. After tests, doctors diagnosed her illness as blood poisoning and kept her several days in the hospital for treatment.

About 80 percent of the bill went directly to the social security administration, the woman said, and she paid the rest.

Cancer is one of a list of about 30 long-term illnesses, ranging from bilharzia to cirrhosis of the liver, for which 100 percent of medical costs are paid by the government health plan. Similarly, treatment of work-connected injuries -- or illness that begins at work, such as an office heart attack -- is paid for entirely.

For most other illnesses, including those requiring hospitalization, from 10 to 20 percent of the costs are borne by the patient. Visits to the doctor, for example, generally are paid directly by the patient, who then is reimbursed by mail for most of the fee.

Many people have joined private insurance groups, requiring fees separate from compulsory social security deductions, in order to pay the gap between total costs and the amount reimbursed by the government.

This is regarded as a way to guarantee the future of private medicine and freedom of choice of doctors or hospitals.

For some patients, however, the result can be higher personal costs for medical care.

What's more, while physicians' fees have been set by the social security administration, some specialists charge higher fees than those set by the government. This means the patient or his private insurance has to pay the difference. Some doctors, particularly those who have acquired special recognition, remain outside the health insurance system entirely, meaning patients must pay the entire cost.

Similarly, social security payments cover only a standard hospital room. Some patients demand private rooms or special services, running the bill beyond social security schedules and increasing the amount they will have to pay from their own pocket.

All this is fueling the escalation of medical costs. While the national health system clearly has broad-based political support, the drain on public funds is a major concern to French officials even as many people seek private insurance to supplement government benefits.

Special correspondent Annie Amirda in the Paris bureau contributed to this report.