Zainsk (Russian:Заи́нск; Tatar: CyrillicЗәй, LatinZäy) is a town in the Republic of Tatarstan, Russia, located on the Stepnoy Zay River (Kama's tributary), 287 kilometers (178mi) east of Kazan. Population: 41,803(2010 Census);41,088(2002 Census);36,621(**** Census).