Officers are investigating the serious assault on a 16-year-old youth in the town on Saturday night between 7pm and 8pm.
They say the teenager was assaulted in the car parking area off Springbells Road in Eden Place after being approached by a group of four males when one of whom then started assaulting him.
The victim was punched and kicked and as a result has been treated for serious facial injuries at Dumfries and Galloway Royal Infirmary.
Police say the four then made off after the assault and Detective Constable Gary Story at Annan said: “This was a vicious and prolonged attack on a young lad which has left him with some serious facial injuries.
“We have been carrying out door-to-door enquiries in the area to establish if anyone might have witnessed this assault.
“I would appeal to the community to come forward if they have any information which would help us catch those responsible.”
He added: “At this time the description we have of the attacker is that he was about 17/18 years old, slightly taller than 5’8” , wearing a North Face zipped hooded top with the hood up and dark jogging bottoms and training shoes.
“Anyone with any information should give us a call at Annan on the 101 number.”