Hard-up students should be allowed to pay off their debts by selling a kidney, an academic has argued.
Sue Rabbitt Roff, a researcher at Dundee University, said it was time to "explore" kidney donors being paid as an "incentive".
Mrs Roff believes the payment should be set at about £28,000 - equivalent to the UK average annual income.
The British Medical Association (BMA) said it would not support cash being paid for organs.
It is currently illegal to pay for organs for transplantation under the Human Tissue Act. The act also makes it an offence to attempt to buy or sell organs for transplant.
In an article for bmj.com, Mrs Roff said a regulated payment system run under "strict rules" would not resemble the illegal markets that exist in many countries.
"It would be an incentive across most income levels for those who wanted to do a kind deed and make enough money to, for instance, pay off university loans," she said.
"We have recently moved to allowing donation of strangers' live kidneys, in which an individual decides to give to someone whom they will never meet and with whom they have no emotional or genetic relationship.
"That is a huge shift from the approach of last century, when it was largely assumed that genetically related members of families would want to donate among themselves."
Three people a day die on the UK kidney transplant list - but the number of donations is not keeping pace with the demand for the organs, according to Mrs Roff.
And the need for kidneys is only likely to rise with the increase in conditions such as diabetes and high blood pressure, she said.
But Dr Tony Calland, chairman of the BMA's medical ethics committee, rejected the call for donor payments.
He said: "Organ donation should be altruistic and based on clinical need. Living kidney donation carries a small but significant health risk.
"Introducing payment could lead to donors feeling compelled to take these risks, contrary to their better judgement, because of their financial situation."
The Human Tissue Authority (HTA) said the organisation would "continue to explore" the issues around living donation that had the potential to increase the number of organ transplants.
But a spokeswoman added: "As relationships between potential donors and recipients become increasingly varied, the HTA must continue to ensure that living organ donation is something people enter into freely and without financial reward."