Riein is a former municipality of the district of Surselva in the canton of Graubünden in Switzerland.
On 1 January 2014 the former municipalities of Riein, Castrisch, Ilanz, Luven, Pitasch, Ladir, Ruschein, Schnaus, Sevgein, Duvin, Pigniu, Rueun and Siat merged into the new municipality of Ilanz/Glion.