Košeca (Hungarian: Kasza) is a village and municipality in Ilava District in the Trenčín Region of north-western Slovakia.

The municipality lies at an altitude of 255 metres and covers an area of 18.943 km².

Part of the cadastral municipality of Košeca is also Nozdrovice.

The records for genealogical research are available at the state archive "Statny Archiv in Bytca, Slovakia" Media related to Košeca at Wikimedia Commons

This Trenčín District location article is a stub.