Kościaszyn [kɔɕˈt͡ɕaʂɨn] is a village in the administrative district of Gmina Dołhobyczów, within Hrubieszów County, Lublin Voivodeship, in eastern Poland, close to the border with Ukraine. It lies approximately 9 kilometres (6 mi) south-west of Dołhobyczów, 35 km (22 mi) south of Hrubieszów, and 129 km (80 mi) south-east of the regional capital Lublin. The village is located in the historical region Galicia.