Sayansk (Russian: Сая́нск; IPA: [sɐˈjænsk]) is a town in Irkutsk Oblast, Russia, located on the Oka River (Angara River's basin) 270 kilometers (170 mi) northwest of Irkutsk. Population: 40,786 (2010 Census preliminary results); 43,468 (2002 Census); 38,169 (1989 Census).