Officers from the Garda arts and antiques unit have recovered a painting by Peter Paul Rubens which was stolen from Russborough House in 1986.
It was one of 18 stolen in a robbery from the collection of the late Sir Alfred Beit at the stately home in Co Wicklow.
Two paintings are still missing after the robbery, thought to have been carried out by a Dublin criminal gang led by Martin "The General" Cahill.
A Garda spokesman said the painting, Head of a Mandated 1650, was recovered on the northside of Dublin.
Since 1974, there have been three robberies from the collection. The first robbery involved an IRA gang and all 19 paintings taken were later recovered. Last year, a gang again raided the house. Two paintings are still missing following that robbery.
The search for all the other missing paintings remains "ongoing", the spokesman said.
Mr William Finlay, chairman of the Alfred Beit Foundation, which now owns the Beit art collection on behalf of the nation, said the Rubens had been restored to them "in very good condition".