Martin Helme will head up the opposition Conservative People's Party of Estonia (EKRE) at the newly sworn-in XV Riigikogu, while the coalition Reform Party's chief whip will be Erkki Keldo.
Helme is also EKRE's leader.
Erkki Keldo replaced Mart Võrklaev, who has been made finance minister in the incoming coalition.
Reform's deputy whips will be former education minister Liina Kersna, and MP Yoko Alender.
Reform now has 37 MPs at the 101-seat Riigikogu.
MPs Siim Pohlak and Helle-Moonika Helme will be vice-chairs of EKRE's party group.
EKRE has 17 MPs at the XV Riigikogu.
As reported by ERR News, Marek Reinaas will be Eesti 200's chief whip, the party's first, after winning its maiden seats on March 5, while former Tallinn City Council Chair Jevgeni Ossinovsi will hold the same post for the coalition Social Democrats (SDE).
Editor: Andrew Whyte, Barbara Oja