A 40-year-old man was assaulted as he walked through an underpass in Oakley Road, Corby, in the early hours of Friday, February 19.
The man was walking through the underpass between 2am and 2.30am when he was tripped up by a man standing in the passageway.
The offender was a black man, around 6ft tall, of stocky build, with a large afro with a comb in the top.
He wore a shell suit with black and white trainers.
Police would like to speak to anyone who may have witnessed this incident or who may have any information about it.
Witnesses or anyone with information is asked to contact police on 101 or Crimestoppers anonymously on 0800 555111.