The transplant of a baboon heart into a California infant known only as Baby Fae made medical history, catapulting a little-known hospital and its researchers into the international limelight. But it also created controversy over the operation's usefulness and propriety.

While heart specialists marveled that the 5-pound baby had survived as long as three weeks before dying of kidney failure, several said yesterday that the transplant was attempted prematurely, that the move to human experimentation was made before there was adequate animal research.

Some questioned whether there had been a sufficient effort by the researchers to inform the baby's family that other options might have been available.

The animal transplant into Baby Fae, made possible by newly available but toxic drugs to suppress the immune system, is another case in which new scientific and technological developments stir difficult questions about how far and how fast science should proceed in applying this knowledge to humans. A similar debate was stirred nearly two years ago when Barney Clark, an elderly dentist, received an artificial heart.

There was much criticism of the Loma Linda University team for essentially carrying out the procedure behind closed doors, not discussing their research widely in advance and limiting information after the Oct. 26 transplant.

"It is premature to comment upon the scientific results until they have had a chance to surface, but this does not seem to be a scientific or clinical breakthrough," said Dr. Peter L. Frommer, deputy director of the National Heart, Lung and Blood Institute.

"The jury's still out" on whether the animal-human heart transplant is advanced medicine or science, said Dr. Michael Hess, director of the Medical College of Virginia's heart transplant program. "I'll tell you this, though. We have no interest in doing it here."

Other heart transplant specialists agreed that it was unlikely that the Baby Fae transplant would stimulate similiar attempts until there is more basic knowledge about how the human body rejects foreign organs.

"I don't think it will have a major impact. It may stimulate other work in animals. But I don't think it will stimulate anyone to put another baboon heart in a baby. Not at this time," said Dr. Adrian Kantrowitz, a Detroit surgeon who attempted the first human heart transplant in the United States in 1967.

Kantrowitz expressed sympathy for the child and family and the medical team. "It was a rather outstanding feat . . . . I must say in all honesty, I did not expect the baby to last 21 days."

But, like many of his colleagues, Kantrowitz said he saw several shortcomings in the Loma Linda experiment. He said that the little-known California team had not published extensively about their animal work in the new field of xenografts -- transplant of organs between different species -- before attempting the operation in a human.

"What we did was publish 20 or 30 papers on what we did prior to the human transplant," Kantrowitz said, while the Loma Linda team had published little before putting a baboon heart in a human baby. "That's a shortcoming. They deprived themselves and their patients of peer review. If they would have shared with us their experience, we could have helped them. It is not clear they were able to get longterm survivors in the laboratory with animals."

Dr. Leonard Bailey, the Loma Linda surgeon who headed the team, has said he did years of work in transplanting hearts between different animal species before attempting a transplant in humans. He also said yesterday that he plans to go forward with other attempts.

But Kantrowitz and others said they feel that "far more basic science" is needed before human attempts are made. "A lot of people are doing basic research in how to eliminate rejection."

One of those doing such research, and one of the few who expressed support yesterday for the Loma Linda effort, is Dr. Keith Reemtsma, head of the Columbia-Presbyterian transplant program in New York. "If you want to take a pot shot, I'm the guy who started all this," he said.

As far back as 1963, Reemtsma transplanted chimpanzee kidneys into six human patients in New Orleans. In the most successful case, the patient lived nine months.

Reemtsma said yesterday he tried the procedure because many patients were suffering potentially fatal kidney failure, and human organs were not yet available. Kidney dialysis, using the artificial kidney, had not yet been developed.

Shortly afterward, James Hardy, a surgeon from Jackson, Miss., who had been impressed with Reemtsma's success, implanted a chimpanzee's heart in a man. The patient died within hours.

By 1965, kidney transplants using organs from cadavers began achieving modest levels of success, and interest in animal donors quickly faded. Reemtsma was one of the few to keep an interest. After moving to New York, he started a research program on transplants between differing animal species.

"I never wavered in my belief that this will be an important area, that someday it will work," Reemtsma said. "Hell, I was getting nine months of survival 20 years ago with the methods we had then."

Although many transplant specialists recognized that animals might provide an abundant supply of useful organs, the problems of rejection by the patient's immune system seemed massive.

In 1967, South Africa's Dr. Christiaan Barnard startled the world with the first attempt to transplant a human heart. His patient, 53-year-old dentist Louis Washkansky, lived 18 days, three days less than Baby Fae.

Despite the brief survival, surgeons in other hospitals were encouraged to try the procedure. Kantrowitz was the first American to do so. Transplant surgeons became a new breed of popular hero.

In 1977, Barnard grafted a baboon's heart into a patient who died within hours and a chimpanzee's heart into another who survived 3 1/2 days. As monkeys, baboons are more distantly related to human beings than are chimpanzees. Barnard said then that he gave up using chimp hearts not because of any technical problems but because he became too attached to the animals being groomed as donors.

Although transplant experts were unaware of any further attempts to use animal organs until the Baby Fae case, they noted that doctors had long hoped that someday it would be possible to use animal donors.

"This has always been felt to be within the realm of reason," said Roger Evans, a medical sociologist at the Battelle Seattle Research Center who heads a federally sponsored study of heart transplants. "There are people who think someday we will have baboon colonies breeding these animals for their hearts. That's probably still a long way off but I feel the Baby Fae case will probably lead to more interest in xenografts than there has been, particularly if the shortage of human organs persists."

Evans said it is estimated that 15,000 people each year would be likely candidates for heart transplants. About 800 heart transplants have been attempted since the procedure was invented.

There is some debate about how available human hearts are for infants like Baby Fae and whether the option of a human heart transplant was adequately explored.

"My feeling is that they should have tried harder to get a human heart," Kantrowitz said, "but I don't think they were interested in that." Dr. Paul Terasaki, director of the California Regional Organ Procurement Agency, is quoted in news reports as saying, "I think they did not make any effort to get a human infant heart because they set on doing a baboon."

Others have noted that another operation to correct the kind of birth defect that afflicted Baby Fae is being attempted with some success by doctors in Philadelphia and Boston. She was born with hypoplastic left heart syndrome, in which half of the heart is missing, and faced almost certain death within weeks.

Loma Linda doctors have defended their effort, saying that they felt it offered a good option for Baby Fae to live and that her life was in immediate danger without their operation.

"Researchers often choose to justify themselves by saying the choice is between death and taking a chance on a new procedure. We've heard this many times," said Arthur Caplan, an expert on medical ethics at New York's Hastings Center. "That's not quite true. The choice is not between life and death, but between a chance at life, the possibility of an impaired life, the certainty of death and the possibility of a slow, painful and lingering death. Those are really the choices that you face ethically."

He charged that Loma Linda had "failed in its obligation" to communicate openly with both the public and the medical community. "I don't think that the way to do animal transplants is to suddenly one day announce it as a fait accompli," said Caplan. And since the transplant, he said, the researchers and their spokesmen had failed to disclose information about the informed consent forms signed by the family and the research design approved by the hospital.

"I hope that other institutions learn from this about the need to communicate clearly," Caplan said.