The Miass is a river on the eastern side of the Ural Mountains in Bashkortostan, Chelyabinsk Oblast and Kurgan Oblast, Russia. It is a right tributary of the Iset, part of the Irtysh basin. It is 149 kilometres (93 mi) long, and has a drainage basin of 13,700 square kilometres (5,300 sq mi). The cities Chelyabinsk and Miass are located on the river.