The incident took place just after 10pm on Wednesday 2nd October 2013 at the newsagent on County Road in Swindon, near to the pedestrian crossing towards the Transfer Bridges.
A male entered the shop and brandished a knife at the shop assistant before emptying the till. The knife has been described as a normal kitchen knife.
The suspect is described as white, of slim build, around 5ft 9in tall and aged no more than 25 years old. He was wearing dark clothing.
A CCTV image of the suspect is attached on the link below.
Detective Constable Matthew Lewis said: “This robbery was committed against a lone shop worker who was working in the small newsagents.
"The offender has grabbed hold of the worker and threatened him with a knife.
"This robbery happened so quickly that the worker did not have any time to react but he remained calm when obviously terrified by a knife wielding attacker.
"I would like to hear from anyone who saw a male like the one pictured running along County Road or the surrounding streets just after 10pm on Wednesday night."
Anyone with information is asked to contact Wiltshire Police on 101, or Crimestoppers on 0800 555 111 where information can be left anonymously.