Under 100 organ transplants were carried out in the UK last month, the lowest number for 36 years figures show.
NHS Blood and Transplant (NHSBT) analysis for BBC 5 Live Investigates showed there were 99 operations in April, down from 244 in March.
The last time the monthly total dropped below 100 was February 1984.
Some specialists fear the fall in the number of operations will cause a backlog of patients needing organ donations, leading to increased waiting times.
Prof Peter Friend, director of the Oxford Transplant Centre, told the BBC Radio 5 Live Emma Barnett show: “Every transplant that does not take place now means that a patient somewhere, and at some point, never receives their transplant.
“This is an inevitable consequence of the fact that the supply