Mrs Mak took the first available train to Guangzhou where she was admitted to the First Affiliated Hospital of the Sun Yat Sen Medical University - the same hospital where Hong Kong multi-millionaire Deacon Chiu had undergone a kidney transplant weeks earlier.

But while Mr Chiu's operation had been pronounced a success, Mrs Mak's went horribly wrong. She suffered what is medically termed a hyperacute rejection - a complete and instant rejection of the new organ. According to the mainland Chinese doctors who performed the operation, Mrs Mak's new kidney turned black on the spot and had to be removed immediately.

She returned to Hong Kong to recover physically and financially. It took time. Despite spending $200,000, Mrs Mak felt she was fortunate to survive her ordeal but she was soon told that because her body had rejected the first transplant so violently another attempt would be difficult.

Another shock was awaiting her. The more doctors she saw, the more the question was raised: ''Was the operation that went so horribly wrong needed at the time?'' The answer, according to a strong body of medical opinion, is no. Leading doctors say the operation was not required because Mrs Mak did not even need kidney dialysis at the time, let alone a transplant. Now Mrs Mak is reporting her doctor to the MedicalCouncil and the profession will be following the case with interest.

It is not often the opinions and actions of a medical expert are called into question. But more significantly perhaps, the case should set off alarm bells for the increasing number of Hong Kong patients who risk death every year by going to China for kidney transplants - a practice condemned by most doctors as an unsavoury trade in human organs, many of which come from the bodies of executed prisoners.

''The matter should not be taken lightly by patients or doctors who refer patients to Chinese hospitals. My mother has suffered in what could eventually be proved to be a premature - if not totally unnecessary - operation,'' said the woman's daughter, who was in China when her mother underwent the failed transplant.

Many experts agree China transplants are matters of concern. Quoting unacceptably high infection and mortality rates, a group of 34 kidney specialists took the rare step of condemning the practice in an open letter in 1991. They insisted it was ''correctand necessary'' for all responsible medical professionals not to encourage such cross-border trips. They said a survey showed more than 50 per cent of patients had not been informed of the risk and the full financial implications of transplants in China.

But Hong Kong people whose kidneys fail face an unenviable choice; they can either endure years of dialysis to cleanse their blood, join a long waiting list to receive a transplant in Hong Kong, or pay $100,000-$200,000 for a package deal to receive a new kidney on the mainland.

Mrs Mak took the latter option and regretted it. Professor Lai Kar-neng, the chief of the renal unit at the Prince of Wales Hospital, is among those who believe Mrs Mak should not have gone to China. He has studied medical records for about the time whenMrs Mak was referred to the Chinese hospital for a transplant in 1991 and they show her level of creatinine, or the accumulative metabolic waste product which her kidneys failed to get rid of, had not reached a point where she would require dialysis.

As dialysis is a form of renal replacement therapy, doctors say the fact she did not require dialysis then was sufficient to show Mrs Mak's kidneys could adequately function about the time of her referral.

''My argument in this case is - judging from her medical record - the patient during the period of her transplant did not require even dialysis,'' he said. ''A patient who does not require dialysis should not be given a transplant.

''A kidney transplant is a major operation. The patient did not need a transplant then. Why not delay the operation until such time when she needs one?'' But more important, suggested Professor Lai, was the fact that Mrs Mak still did not need dialysis more than a year after her failed transplant in China. ''When you perform a transplant you are committing the patient to the risk of surgery, and the risk of immuno-suppression,'' he said.

''You are committing the patient to a potential risk of infection. Mrs Mak's is a progressive disease, not an aggressive one. There was no urgency to jump the gun and have a transplant done on her then. Her condition actually illustrates the transplant may not be necessary at that time. Mrs Mak at the time clearly did not require a transplant.'' Dr Peter Chan, a Prince of Wales surgeon responsible for kidney transplants, echoed the view that when patients did not need dialysis, they did not need a transplant. Dr Chan said judging from the patient's medical record some two months after the failedtransplant, the transplant could be regarded as ''premature or not yet necessary at the time''.

He said only under exceptional circumstances might a kidney transplant be carried out without a period of dialysis. Before deciding on pre-emptive transplant, the doctor would have to be certain the patient suffered chronic renal failure after a long period of observation; that the patient was young; and that a well-matched living related donor, such as parents or siblings, was available.

''This is the international standard on the management of patients with chronic renal failure,'' Dr Chan said.

The doctor who referred Mrs Mak to China, who cannot be named for legal reasons, remains adamant he had her best interests in mind and referred her to China because her creatinine level had risen sharply. He brushed aside criticism, saying: ''There is nouse asking the surgeons [for opinion]. In Hong Kong, nobody is really [specialised] in this field. I don't mind you criticising me for my charges. As a top doctor, I will not charge cheaply. But I will never do anything which is not necessary.'' He said he once had a case where a patient was referred to him by a Vancouver consultant for a pre-empted transplant to be performed in Hong Kong. The difference between that case and Mrs Mak's was the Vancouver patient had a kidney donated by a living donor.

He said he referred Mrs Mak to China because she had expressed repeatedly she wanted to avoid dialysis and that, at the time of the referral, her kidneys were approaching a stage when they would stop working. ''Her creatinine level was rising so fast that she could need end-stage dialysis anytime,'' he said. If there was a living related donor, he said, Mrs Mak could have waited until symptoms arose before she had surgery. But because she was getting her kidney from the dead, she had to grab the opportunity when it arose. As the waiting list to receive a transplant in Hong Kong was long, Mrs Mak was left with no choice but to go to China.

The doctor did admit, however, that mistakes might have been made. ''Maybe I have made a mistake for recommending an ungrateful patient,'' he said. ''I am not God . . . I can also make mistakes. Looking back there might be a mistake because you said she did not require dialysis [for a long time after the operation]. But any qualified specialist seeing the creatinine level rising in a short time from 600 to 800, and that the patient was opting only for transplant, will recommend a transplant.'' He said Mrs Mak was the only one of the three patients he had recommended for the pre-emptive procedure who did not benefit, but admitted he would think hard before he recommend a fourth patient. ''Pre-empted transplant is a totally acceptable practice .. . but this story has taught me a lesson,'' he said. ''Next time if a patient comes to ask me for a pre-empted transplant I will not do it unless he or she is a trusted friend. Why should I recommend a total stranger? There is no use being nice. I recommend these patients out of goodwill.'' He would not reveal how many patients he had referred to China for transplants. He said he never received any commission for such referrals. ''By putting patients on dialysis for six months I can make a lot of money,'' he said. ''If I want to make money,why should I bother to send you to a pre-empted transplant? You think about it. In the case of Mrs Mak, if I put her on dialysis when she first came to me and sent her to transplant only now, she would have been on dialysis for two years. Why should I sendher to a pre-empted transplant?'' He said the transplant in China had an estimated 90 per cent immediate success rate although when the rejection rate after the first month was taken into account, the figure could come down to about 80 per cent. ''The figure was no different from Queen Mary's results [in Hong Kong],'' he said. ''A patient should realise they may not be among the 80 per cent. I tell them if the operation fails, they can lose both money and their lives.'' He said people who were prejudiced against transplants in China should note certain forms of dialysis had a mortality rate similar to that of transplants in China. ''But think about the quality of life when you have a successful transplant. That people are biased against transplants [in China] is beyond me,'' he said. ''I am a doctor. I don't want to get carried into the politics. I just want to take care of the patients to the best of the patients' interests. Anything that is legal I would do it.'' He described hygiene conditions in Chinese hospitals as ''a market place'' although he said there had been improvements. ''There is nothing else you can do except choose not to go [if you are not happy with the conditions],'' he said, adding he would warn patients of the risks involved in transplants in China before sending them there.

The concerns do not stop there. Many Hong Kong doctors regard the quality of tissue typing - a method of matching tissue as closely as possible between the donor and the recipient to minimise the risk of rejection - is also difficult to check.

There are other ethical concerns. Many transplant organs in China come from the bodies of executed prisoners. Documents obtained by the Sunday Morning Post show the practice has been condoned by the Chinese authorities for almost 10 years. One document includes chilling details of how the ''harvesting of organs'' should be carried out at execution sites and a requirement that the practice be kept in ''strict confidentiality''.

Mrs Mak said she had been told by one Chinese doctor the kidneys came from executed prisoners. ''If a criminal was to be executed tomorrow, he would have a blood test today,'' she said. Her daughter said on the day of Mrs Mak's operation, she had seen staff carrying what looked like an ice box to the operating room. ''My mother with other patients who were to have the transplant done on the same day had been waiting in the operating room for a long time. I was wondering what was the delay.'' The whole sorry experience has left Mrs Mak and her family with deep physical, emotional and financial scars. Mrs Mak said the family had borrowed from friends to pay the operation fee of $70,000 in the Chinese hospital. ''But we had spent much more than that. In all some $200,000 including transport and accommodation,'' she said.

''I don't mind the money being spent. I was so full of hope when the doctor told me there was a kidney for me. My family did not tell me my transplant had failed until after I returned to Hong Kong. They were worried I would be very upset. I was shattered. Now I am left with an ugly scar on my stomach. I am also without hope. I will continue to be a burden to my children, until the day I die.'' Next time if a patient comes to ask me for a pre-empted transplant I will not do it unless he or she is a trusted friend. Why should I recommend a total stranger? There is no use being nice. I recommend these patients out of goodwill