An armed man held up staff at a city centre post office before fleeing with 5,000 euro in a taxi.
The raider was carrying a gun when he went into the post office on Merrion Row in Dublin and threatened staff.
No one was injured during the ordeal.
A Garda spokesman said the suspect then walked to a nearby hotel where he got into a light blue coloured Skoda taxi, which turned on to Baggot Street.
The suspect is described as about 50 years old. He spoke with an English accent and was of a heavy build and wore glasses, a dark jacket and hat.