Someş (Hungarian: Szamos) is one of the most important rivers of Transylvania. It flows through Romania and Hungary.

There are two headstreams, Someşul Mare (Hungarian: Nagy-Szamos), rising from the Rodnei Mountains (county Bistriţa-Năsăud) and Someşul Mic (Hungarian: Kis-Szamos), rising from the Apuseni Mountains (county Cluj), which is in turn formed by the confluence of another two rivers: Someşul Cald (Hungarian: Meleg-Szamos) and Someşul Rece (Hungarian: Hideg-Szamos).

The two streams meet at Dej and flow westward, through Satu Mare, to join the Tisza in Hungary, near Vásárosnamény .

The river Someş was known to the Romans by the name Samus.