A man approached the counter of the Scotbet shop in Ferry Road, Edinburgh, at around 6.30pm yesterday with a handgun.
He gave a member of staff a note demanding money but left empty-handed after the worker refused.
Police believe the incident could be linked to an earlier armed robbery at a BP petrol station at the Leith end of Ferry Road at about 10pm on January 18 in which £300 was taken.
CCTV images of a man suspected of carrying out that robbery were released by police earlier this week.
Detective Sergeant Lynsey Thomson said: “While this robbery was unsuccessful, this incident was very distressing for the member of staff and we are keen to trace the suspect as soon as possible.
“We also believe that this incident may be linked to a previous incident that happened at a petrol station last week, also on Ferry Road.
“Any witnesses who may have seen the suspect, or who recognise the description of him, are asked to come forward.”
The suspect in the bookmakers incident is described as a white man in his mid-40s, around 5ft 5ins with a slender build.
He was wearing a black hat, which peaks at the top, waterproof black gloves, a khaki green jacket, dark jeans with faded patches and turn-ups as well as brown ankle boots.