Splügen (Romansh: Spleia, Italian: Spluga) is a former municipality in the Viamala Region in the Swiss canton of Graubünden. On 1 January 2006 Splügen incorporated its neighbouring municipality of Medels im Rheinwald . On 1 January 2019 the former municipalities of Hinterrhein, Nufenen and Splügen merged to form the new municipality of Rheinwald.

In 1995, the Swiss Heritage Society bestowed the Wakker Prize to Splügen.

Splügen is first mentioned about 840 as cella in Speluca.

Splügen has an area, as of 2006, of 60.5 km2 (23.4 sq mi).