A 71-year-old man was punched in the face and knocked to the ground in Matlock.
The victim had arrived in the town by bus at about 5.30pm on Friday, April 1.
He was walking along Dale Road when he was assaulted by a man who punched him to the face, knocking him to the ground.
Staff at a nearby shop called for an ambulance and the victim was taken to Chesterfield and North Derbyshire Royal Hospital, suffering a broken nose.
Police are appealing for witnesses to the assault to come forward.
The offender was described as white, aged in his late 40s, between 5ft 9ins and 6ft tall and of stocky build.
Anyone who recognises the description of the offender or who saw the assault take place should call PC Gareth Buxton on 101, quoting crime reference 14295/16 or alternatively, contact Crimestoppers on 0800 555 111.