The 49-year-old was assaulted by two men in the Back Rampart area around 1.30 pm on Sunday.
The victim was taken to the town’s Galloway Community Hospital for treatment to a cut head.
Police Scotland have issued descriptions of the attackers.
The first is described as 32 to 33 years of age, five feet 11 inches tall, well built, short hair, wearing a dark hooded top, denims, Nike trainers and a baseball cap.
There was only a limited description for the second man, who was said to be 28 or 29 years of age with short brown hair.
Detective Constable Keith Kennedy, of Stranraer CID, said: “We want to hear from anyone who was in the area of the Back Rampart around this time and saw anything which might help us identify these two men.”
Information should be passed by phone through the 101 non-emergency number.