A man armed with a revolver pistol stormed a Ballymun bookies at the weekend.
The incident happened shortly before 6pm on Sunday evening.
He stole a small sum of cash from the shop before fleeing the scene on foot.
A Garda investigation is underway, Dublin Live reports.
In another incident at the weekend, a man wielding a samurai sword attempted to rob an off-licence in Santry.
He was tackled to the ground by the security guard from the pub next door, and fled empty-handed.