Hinterrhein (Romansh: Valragn) is a village and a former municipality in the Viamala Region in the Swiss canton of Graubünden. The village is located near the start of the river Hinterrhein/Rein Posteriur, one of the two initial tributaries of the Rhine . On 1 January 2019 the former municipalities of Hinterrhein, Nufenen and Splügen merged to form the new municipality of Rheinwald.

Hinterrhein is first mentioned in 1219 as de Reno.

Hinterrhein has an area, as of 2006, of 48.4 km2 (18.7 sq mi). Of this area, 22.7% is used for agricultural purposes, while 7.6% is forested.