Andrew Malcolm, 46, was last seen on Bolam Place, Bedlington, at 8.40pm on Tuesday, February 5.
Officers are growing increasingly concerned for his welfare and are keen to make sure he is fit and well.
Andrew is described as white, of stocky build with a bald head. He was last seen wearing a navy blue T-shirt, black jeans, a black hoodie and black Timberland boots.
?It is believed he may have travelled to the Dumfries and Galloway area of Scotland.
Andrew, or anyone who has seen him, is asked to call 101 quoting reference 1186 060219.