The Romen (Ukrainian: Ромен; Russian: Ромен) is a right tributary of the Sula with a length of 111 km and a drainage basin of 1,645 km². It begins in the northern Ukrainian Oblast of Chernihiv and flows into the Sula near the Sumy Oblast city of Romny. The average discharge quantity amounts to 3 m³/s at the delta.

The name is of Baltic origin, cognate with the Lithuanian romus ('quiet').