The Tamir River ( ) is a river flowing through the valleys of the Khangai Mountains in Arkhangai Province, Mongolia. The river is the namesake of the Mongolian literature classic by Chadraabaliin Lodoidamba, The Clear Tamir River ().
For most of its length, the Tamir is divided into two branches: the Northern Tamir () and the Southern Tamir ().
The Northern Tamir starts between the Shalkhagiin Khoit mountain range and the Togoo Mountain in the Ikh-Tamir. The southern Tamir starts about 25 km to the south-west in the Bulgan at the end of the Khairkhnii mountain range. The two branches run a roughly north-eastern course up to their confluence at the district center of Battsengel.
The Tamir is a main tributary of the Orkhon River, which it meets in ÃÂgii Nuur, opposite to the namesake ÃÂgii Lake.