Edward Giles – believed to be known as Ted – was last seen at around 8.45am today (Tuesday, April 24) leaving the Royal Lancaster Infirmary.
He was initially admitted to the hospital showing signs of confusion but left the site 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.
PC Iain Arnott, of Lancaster Police, said: “We are extremely worried about Ted and are urging anybody who has seen him, recognises him, or knows where he may be to contact us as soon as possible.”
Mr Giles is described as white, approximately 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.
Anybody with information should contact police on 101 quoting log number 317 of today (April 24).