The Trotuș is a river in eastern Romania, a right tributary of the river Siret. It emerges from the Ciuc Mountains in the Eastern Carpathians and joins the Siret in Domnești-Sat near Adjud after passing through Comănești and Onești in Bacău County. The total length of the Trotuș is 162 km. Its basin area is 4,456 km2.
