The Domleschg (Romansh: Tumleastga) is a valley in Graubünden in Switzerland . Geographically, the name "Domleschg" covers both sides of the valley. Politically, the villages on the left bank of the Posterior Rhine form the Kreis (sub-district) of Thusis and those on the right bank form the Kreis of Domleschg. Thusis is the main village in the valley. The northernmost locality is Rothenbrunnen , the southernmost is Sils.

The following municipalities lie in the Domleschg valley (the first name is the German name, the second is Romansh):

The Posterior Rhine emerges from the Schams (Romansh: Schons) valley.