Sir Terence English, who performed the UK's first heart transplant, has offered his support to an influential steering committee that backs assisted dying.
"A doctor has responsibility first to the patient and, if I knew that patient was terminally ill, was of sound mind and hadn't been got at by friends and relatives, I would be prepared to assist him or her," Sir Terence said.
His comments come after director of public prosecutions Keir Starmer last year clarified the legal position on assisted dying.
The move was interpreted by many as a clear indication that friends and family were unlikely to face prosecution if motivated by compassion to help a relative or close friend with a "clear, settled and informed" wish to die.
It came after a lengthy legal battle by Bradford campaigner Debbie Purdy who wanted to know if her husband, Cuban musician Omar Puente, would face jail if she ever required help ending her life. She argued that if there were such a risk, she would be forced to end her life sooner so as to avoid him becoming involved.
The multiple sclerosis sufferer is still battling for a formal change in the law to make assisted suicide legal in certain circumstances so a tribunal can decide beforehand if assistance is appropriate.
Sir Terence, who has joined the Healthcare Professionals for Assisted Dying (HPAD) group, added: "I would want there to be safeguards. I would want to have a doctor who had not been involved with their care, who had been registered for five years, who would confirm mental capacity of the patient, that they were sound of mind.
"I would also wish to ascertain that no pressure had been put on him or her by the family and, if in any doubt at all, involve a psychologist."
Sir Terence, a former president of the Royal College of Surgeons and the British Medical Association, performed the UK's first successful heart transplant in 1979.
The HPAD is supporting the campaign group Dignity in Dying which has been calling for a range of measures to allow for what it describes as a "good death", including the option of an assisted death for terminally ill, mentally competent adults. Backers include comedienne Jo Brand, author Sir Terry Pratchett, and Falklands veteran Simon Weston.
HPAD wants changes to the law and medical practice to doctors have greater freedoms to assist terminally ill patients at the end of their life.