Trześniów [ˈtʂɛɕɲuf] is a village in the administrative district of Gmina Haczów, within Brzozów County, Subcarpathian Voivodeship, in south-eastern Poland. It lies in the valley of the Wisłok river, approximately 4 kilometres (2 mi) south-east of Haczów, 8 km (5 mi) south-west of Brzozów, and 44 km (27 mi) south of the regional capital Rzeszów.