Edward Giles – also known as Ted – was last seen around 8.45am yesterday (Tuesday, April 25) leaving Royal Lancaster Infirmary (pictured).
He was initially admitted to hospital showing signs of confusion but left before he could be fully assessed.
He was brought to hospital from Windermere and had mentioned having links to Bournemouth, although his home address is currently unknown. He may also be known by a different name.
Despite an initial appeal for information yesterday, Mr Giles has yet to be found and detectives are growing increasingly worried for his welfare.
Det Insp Andy Ellis, of Lancashire Police, said: “We are now seriously concerned about Mr Giles and are appealing for the public’s help in locating him.
“The circumstances of his disappearance are very worrying. He has arrived at hospital in a confused state, left before he could be fully assessed and went missing without providing more personal details to staff.
“We do not believe he has any money or a mobile phone with him, which is making it more difficult to trace him.
“At this stage we have little more information to go on. I would ask anyone reading this appeal to study the pictures provided and be mindful he is a missing man.
“It is likely he is still in and around the Lancaster area. If you have seen him or know his whereabouts, call us immediately.”
Mr Giles is described as white, 6ft tall and of stocky build. He has grey hair and is currently clean-shaven. He was last seen wearing a navy blue anorak over a blue and white striped shirt, dark denim jeans and brown shoes.
Anyone with information should contact police on 101 quoting log number 317 of April 25.