The Duke of Edinburgh told a Filipino nurse her country must now be "half-empty" as "you're all here running the NHS" during a visit to Luton and Dunstable University Hospital on Tuesday.
Philip, who is famed for his gaffes, made the hospital worker from the Philippines laugh with his comment during a visit to open a cardiac centre.
A spokeswoman for the hospital described the royal visit as a huge boost for staff morale and said the Duke was in a jovial mood, making jokes throughout his tour.
Philip was in a 'jovial mood', said hospital staff
Philip had a stent fitted to clear a blockage in a coronary artery in December 2011 and when, during the visit, he was given a gold plated stent, he quipped that he now had a spare.
The Duke is well-known for his outspoken comments and famously told British students during a 1986 state visit to China: "If you stay here much longer, you'll all be slitty-eyed".
He also once told a group of deaf youngsters: "Deaf? If you are near there, no wonder you are deaf," referring to a school's steel band.
He also told Susan Edwards, who is blind, uses a wheelchair and has a guide dog: "Do you know they have eating dogs for the anorexic now?"
The hospital spokesman said of Tuesday's visit: "Staff greatly enjoyed the opportunity to meet the Duke of Edinburgh, and we regard all personal conversations he had with our staff and guests as private and therefore would not comment on them."
Buckingham Palace said it did not comment on private conversations.