James Morris was admitted to hospital with a broken leg in 1962 at the age of 21 but never went home after suffering a cardiac arrest on the operating table.
He was left in a vegetative state after the operation and was moved to Wester Moffat Hospital in Airdrie, North Lanarkshire.
The Army veteran, who could only say three words, died in April aged 75, the BBC reported.
His brother Karl Morris, 62, said a member of staff from Wester Moffat had suggested that no-one had been in care in a single hospital longer than James.
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"He only ever learned how to say three words again - his three loves - 'home', 'pub' and 'horses'.
"We often took him on holidays in Britain and the hospital knew how much he loved the pub so they would even take him there now and again."
James was serving in the Scottish Rifle regiment, the Cameronians, in Germany when he was injured in a car crash.
He only broke his nose and thigh bone in the crash but part of his brain shut down during the operation on his thigh.
"Having spent such an extraordinarily long time at the hospital, Jimmy touched the lives of many. He was a good confidant and a great character and he will be sorely missed by everyone at the Heather Ward."
Wester Moffat Hospital confirmed James had spent 54 years in their care after spending two years in other hospitals.
A spokesman of the National Health Service (NHS) said they were not aware of anyone having spent longer than 54 years in an NHS hospital.
Karl Morris has praised the "unbelievable" staff at the hospital for the care they gave his brother.