A 28-year-old man was knocked unconscious after he was punched in the face during an attack in Northampton town centre.
The man was assaulted in Gold Street, Northampton, shortly before 5am on Saturday, March 5.
A police spokesman said several members of the public stopped to help the victim and the offender ran off.
The offender, who is believed to be known to the victim, was in his early 20s, of chubby build, with short dark hair and was wearing a black, long sleeved top and blue jeans.
Police officers would like to speak to anyone who may have witnessed this incident or who may have any information regarding it.
Witnesses or anyone with information can contact police on 101 or Crimestoppers on 0800 555 111.