The man was on East Main Street in Blackburn, West Lothian, when two men came up to him and struck him in the face.
The injured man fell into the road.
Police said the incident, which happened on January 19, has just been reported to them.
They appealed for information about the attack which took place near the premises of Matt Purdie and Sons Removal and Storage Company at around 5.30pm that day.
The suspects are described as being in their late 20’s and wearing dark clothing. One of them was wearing a hat.
Detective Constable Craig Waddell, of Livingston CID, said: “This incident has just been reported to us and we are keen to hear from anyone who was in the vicinity at the time and remembers seeing anything suspicious.”