Leinster turned professional along with the teams representing the other Irish provinces in 1995 and has competed in the Celtic League since it was founded in 2001, having previously competed in the annual interprovincial championship. Leinster A competes in the British and Irish Cup. Leinster has twice been Celtic League champions and twice been Heineken Cup winners.
On 21 May 2011 Leinster won its second Heineken Cup with a thrilling 33-22 victory over Northampton Saints. Leinster is currently ranked 1st place in the ERC European Rankings.