Buying kidneys and other organs is illegal but authorities cannot stop people going overseas on "transplant tourism" trips.
The Health Ministry's acting clinical services manager, Nick Polaschek, said the Human Tissue Act stops people buying organs.
"Whatever their physicians may advise, there is nothing to stop a New Zealander who wishes to do so from going overseas to purchase a transplant, as a few in fact do," Mr Polaschek said.
About 500 people around New Zealand are waiting for a kidney transplant while last year there were 121 kidney transplant operations - 54 coming from dead donors and 67 from live donors, according to Organ Donation New Zealand.
But some Kiwis are avoiding the lengthy waits and heading overseas to buy a kidney and have the operation performed.
"The Ministry is aware of news reports about some people going overseas for organ transplants. There are obvious risks to this practice, and a patient's own physician will advise them about these if they are considering this course of action," Mr Polaschek said.
Dr Ian Dittmer is the clinical director at Auckland Hospital's renal clinic.
He told nzherald.co.nz yesterday that a New Zealand patient who went overseas for a kidney operation later died after contracting hepatitis.
Dr Dittmer said other patients have come back with infections and there are other cases where the transplant has not taken.
He said going overseas for a transplant is "abhorrent" and needed to be stopped.
Dr Dittmer is a member of the Declaration of Istanbul - a group of renal physicians who meet to discuss the ethics of transplant tourism and organ trafficking. He has just returned from a meeting in Cairo.
He said often the donors are paid a fraction of that they're promised and are "dumped back in the street again" without ongoing medical treatment.
Another senior Auckland doctor said that he had dealt with two cases in which New Zealanders had bought kidneys and had the transplant operations in the Third World - and he knew there were others.
"They are very rare, but it happens," said Associate Professor Johan Rosman, chief medical officer and renal physician for Waitemata District Health.
"They come back to us and we say, 'Where have you been? You've been away for six months?' [They say] 'Yeah, I've bought me an organ'.
One of the NZ patients had a badly done transplant, and the other had a successful operation.
"It's always the same thing - they say, 'We're going to buy a kidney', and all of a sudden they're gone, they don't come for dialysis any more. Then they show up and they have the kidney."
Professor Rosman, a speaker at a conference on NZ's low organ-donor rate held in Wellington yesterday, said he did not approve of the practice and would never recommend it, but there was no point in ignoring it.
He proposed allowing people to buy organs, but setting up a safe hospital in a Third World country so they could receive healthy organs and be well cared for.
The United Nations has called for an international treaty to prevent the trafficking of organs. A study by the UN last year argued that people should not be able to sell organs and the practice often exploited the poor.
Amnesty International has highlighted "organ harvesting" of prisoners facing the death penalty and has said there is a lack of transparency about whether or not permission has been gained by prisoners.