Nara River (Russian: Нара) is a river in the Moscow Oblast and Kaluga Oblast in Russia. It is a left tributary of the Oka River. The length of the river is 158 kilometres. The area of its basin is 2030 km². The Nara River freezes up in November-December and stays under the ice until April. The cities of Naro-Fominsk and Serpukhov are located on the Nara River.