Officers said Kamil Mrzyglod, aged 34, is Polish with a tanned complexion, slim and 5ft 9ins tall.
He was wearing mint green jogging bottoms with a white cord around the middle, a grey hooded top with a Union Jack on the front, red socks and white trainers. He has two tattoos - one of the word 'Love' on one of his fingers and a tattoo of a cat on his ankle.*
He was confirmed to be seen leaving Scunthorpe General Hospital at 5.30pm on Friday.
Officers said he "is vulnerable, and he is in need of help".
He was visiting the area from West Yorkshire and police are appealing for anyone in the Scunthorpe area or West Yorkshire that knows of his whereabouts to call them on 101 quoting log 531 of March 30.