LONDON (Reuters) - Prince Philip, the 91-year-old husband of Britain's Queen Elizabeth, left hospital in Scotland on Monday after a five-night stay during which he had treatment for a bladder infection.

Smiling and looking sprightly, the prince, wearing a summer blazer, shook hands and thanked staff at Aberdeen Royal Infirmary before giving a cheery wave and climbing into a car with royal aides.

It was the third time in eight months that Philip had been in hospital and the second time he had had treatment for a bladder infection.

The previous occasion was in June during celebrations to mark Elizabeth's 60 years on the throne, after the royal couple had watched a 1,000-boat flotilla on the River Thames from a royal barge, braving chilly, rainy weather.

Last Christmas, Philip spent four days in hospital and had an operation to clear a blocked artery in his heart after suffering chest pains.

A Buckingham Palace spokeswoman said Philip would now rejoin the queen for their holiday at Balmoral, the royal family's Scottish residence. The prince is also expected to resume his official duties, she said.

(Reporting by Michael Holden, editing by Tim Pearce)