Kilmez River (Russian: Кильмезь) is a river in Udmurtia and Kirov Oblast in Russia, a left tributary of the Vyatka River. The length of the river is 270 km, the area of its drainage basin is 17,200 km². The Kilmez freezes up in November and remains icebound until the second half of April. Its main tributaries are the Lumpun, Loban, and Vala rivers.