Around 4.30pm staff in the TV building were told they had to leave the premises.
It is understood that a caller phoned a number of media outlets claiming to have put a bomb in the car-park at RTE. The caller refused to give his name.
Donnybrook gardaí are investigating the threat but it is believed gardaí did not order the evacuation of the building.
Gardaí are on the scene on the Donnybrook campus and a search of the area was ordered.
RTE Radio One continued to broadcast as normal during the evacuation.
Staff have been allowed to return to the building and gardaí confirmed to Independent.ie that the scare was a hoax and nothing was found during a search of the area.
The state broadcaster is due to issue a statement shortly.