A man was hit in the head before being punched to the ground during a robbery in Mill Road, Kettering, on Sunday, November 4.
Sometime between 5am and 5.50am, a 25-year-old man was walking along Mill Road, when he walked past three white men.
He was then hit in the head before being punched to the ground.
Cash was stolen from him before the offenders made off.
The victim was taken to hospital with facial injuries.
Officers would like to speak to anyone who witnessed this incident or has any information about it.
Witnesses to this incident, or anyone with information about it, can call Northamptonshire Police on 101 or information can be given anonymously to Crimestoppers on 0800 555111.