Munster Rugby and the IRFU have confirmed that Dave Kilcoyne and Kevin O'Byrne have extended their contracts with the province.
Loosehead prop Kilcoyne has signed a three-year extension with hooker O'Byrne signing a two-year deal.
Limerick native Kilcoyne has scored 21 tries in 182 Munster appearances and has earned 39 Ireland caps, including five Rugby World Cup appearances this year. The former Ardscoil Rís man has featured in all 10 of Ireland's most recent internationals.
A product of the Greencore Munster Rugby Academy, the UL Bohs clubman made his senior debut against Connacht in December 2011 and won the British & Irish Cup with Munster A in 2012.
He made his European debut in October 2012 away to Racing 92 and started in seven of Munster's eight European Cup games that season.
Cork-born O'Byrne has also signed a contract extension having scored three tries in 67 Munster appearances.
A product of Highfield RFC, O'Byrne captained the Munster U18 Clubs side for the 2008/09 Interpros and was part of the Highfield U18s All Ireland winning squad in 2009.
He has also lined out for PBC, UCC and UL Bohs and made his Munster debut against Edinburgh in September 2014.