The NHS Blood and Transplant has called on people to discuss organ donation with friends and family, after a survey revealed that three fifths of people (60%) have never done so.
Currently only 28% of the UK population is on the NHS Organ Donor Register, a spokeswoman for NHSBT said.
Professor Geoff Beattie, head of school and dean of psychological sciences at the University of Manchester, said: “The figures released by NHSBT show again that the UK public is reserved when it comes to opening up about their feelings.
“Organ donation is a tricky subject to talk about so many people choose to ignore it rather than face the reality.”
Almost a third of those people (30%) do not discuss it because they do not consider it a priority, and 25% of them just do not want to think about it, the study found.
Three people die every day before a suitable organ is found and almost 8,000 people are on the waiting list for a transplant.
National Transplant Week, raising awareness of the issue, starts on Monday.
The survey of 2,000 UK adults was conducted by Tickbox in June on behalf of NHSBT.