Zalewsze is a village in the administrative district of Gmina Kodeń, within Biała Podlaska County, Lublin Voivodeship, in eastern Poland, close to the border with Belarus. It lies approximately 6 kilometres (4 mi) south of Kodeń, 38 km (24 mi) south-east of Biała Podlaska, and 99 km (62 mi) north-east of the regional capital Lublin.