Kevin Webb, 61, was last seen leaving his home in Swinton at 8.15pm on Sunday.
A police spokesman said his family had not heard from him since Sunday and were growing increasingly concerned.
Kevin is described as being between 5ft 10 and 5ft 11in tall, of slim to medium build with short blonde hair.
He was last seen wearing glasses, a black t-shirt, blue jeans, a grey jumper and grey trainers.
If you have seen Kevin or can help officers trace him, call 101 quoting incident number 121 of June 3.