Isamaa was renamed from IRL (Pro Patria and Res Publica Union) in June 2018. Before that, Isamaa was called IRL that was mereged in July 2006 as a union of two centre-right parties, Isamaaliit and Res Publica.
Isamaaliit (Pro Patria Union) was a federation of two parties consolidated in December 1995 – Pro Patria and the Estonian National Independence Party (the first non-Communist political party in Estonia established in 1988). Then party leader Mart Laar was Prime Minister for a second time from March 1999 until January 2002. In the European Elections 2004 Pro Patria Union achieved a successful result, taking Tunne Kelam, then Chairman of the PPU, among six Estonian members of the European Parliament. In April 2005 Tõnis Lukas became the Chairman of the Pro Patria Union.
Res Publica was established in 1989 as a club for young political enthusiasts. Res Publica as a party was founded in 2001 and gained the second best result across the country in the 2002 local elections. In the 2003 parliamentary elections Res Publica gained 28 seats and became the biggest faction in the 101-strong Riigikogu. From 2003 to 2005 Res Publica was the leading force in Estonia’s coalition government with its then president Juhan Parts as Prime Minister. Taavi Veskimägi was elected Chairman of Res Publica in 2005.
In 2007 March election Pro Patria and Res Publica Union gained 19 seats (out of 101) in the Riigikogu and became a junior partner in the Coalition Government. In the Party Congress of May 2007 Mart Laar was elected chairman of the merged party. In 2011 parliamentary election IRL increased the number of seats to 23, and continued as a junior partner in a coalition. In party congress in January 2012 Urmas Reinsalu was elected new party chairman. In 2015 general elections IRL gained 14 seats. In June 2015 Margus Tsahkna was elected chairman. Margus Tsahkna decided not to run again for the chairman in 2017. In May 2017 Helir-Valdor Seeder was elected chairman of IRL and he continues to serve as a chairman of Isamaa (new name since June 2018).