A 28-year-old man from Brierfield is missing.
Inam Ghous was last seen at about 1-20pm on Thursday at Blackburn Hospital.
He is described as Asian, 5ft 6in tall with black hair, facial hair and is of slim build.
He was last seen wearing a long grey coat, pink T-shirt, burgundy jeans and grey trainers. He was also wearing a cream and red hat and a red and blue scarf.
Inam has links to the Brierfield and Nelson areas but also links to Bradford and London.
A Lancashire Police spokesman said: "Inam has been missing for several days now and we are concerned for his welfare. We are urging anyone with information leading to his whereabouts to call us."
If you can help, please call Lancashire Police on 101 quoting log reference 934 of 29th June.