Thieves posing as council employees have targeted a 70-year-old man at his home in Alva, Clackmannanshire.
Two bogus callers said they were there to check central heating systems, but the householder discovered cash missing after they left.
Both men were described as being "scruffy", aged about 40, and 5ft 8in, of medium build.
Central Scotland Police appealed for anyone with information to contact them.
A spokesman said one of the suspects had short, fair hair and an English accent. The second had short, dark hair and a Scottish accent.
Police said they also wanted to trace a third man seen in the area at the time.
He is described as being about 40, about 6ft, of slim build and with receding grey hair. He was wearing a grey jumper and light blue jeans.