The Mureş (in Romanian, in Hungarian: Maros, in German: Mieresch) is an approx. 725 km long river, rising in the Giurgeu Range in the Eastern Carpathian Mountains, Romania. It joins Tisza River at Szeged, in southeast Hungary. It flows through the Romanian counties Harghita, Mureş, Alba, Hunedoara and Arad, and the Hungarian county Csongrád. The cities Reghin, Târgu Mureş, Aiud, Alba Iulia, Deva, Arad (all in Romania), Makó and Szeged (both in Hungary) lie on the river Mureş.

Known as river Marisus in antiquity.