Two US doctors have suggested the sale of organs such as kidneys should be legalised to meet the rising demand.
About 400 people a year die in the UK waiting for organs
They said bids to increase the donor pool were failing, and a black market in organ sales was booming.
Writing in Kidney International the pair said, while it remained a taboo, legalisation should be considered.
But experts in the UK - where selling organs is illegal - said such a move was unnecessary and would exploit the poorest sections of society.
About 400 people a year die in the UK because they are left waiting for a donor, despite the fact that 13m people are signed up to the register.
UK Transplant, the NHS body responsible for the register, said in many cases organs were prevented from being donated because the families were unaware of the donor's intentions.
A spokesman said efforts were being made in the UK to encourage people to join the register and talk about it with their families.
And while refusing to take a position on selling organs, he said: "It is a tragedy that the critical shortage of organs donated for transplant means this question arises at all."
Eli Friedman, a kidney specialist, at the State University of New York, and Amy Friedman, a transplant specialist, of Yale University, said the case for legalising kidney purchases hinged on the fact that individuals were entitled to control their own body parts.
They said: "Strategies to expand the donor pool - public relations campaigns - have been mainly unsuccessful.
"Although illegal in most nations, and viewed as unethical by professional medical organisations, the voluntary sale of purchased donor kidneys now accounts for thousands of black market transplants."
The doctors suggested a figure of about £23,000 for a kidney, with an agency being set up to regulate the market.
But Dr Michael Wilks, chairman of the British Medical Association's ethics committee, said there was universal opinion against selling organs.
"It is exploitative, particularly for the third world, if you had an unfettered global market, and what is more it is not necessary.
"If we had more investment in transplantation services and intensive care and changed the law so we had presumed consent we could meet need."