Werdun [ˈvɛrdun] is a village in the administrative district of Gmina Tarczyn, within Piaseczno County, Masovian Voivodeship, in east-central Poland. It lies approximately 9 kilometres (6 mi) west of Tarczyn, 25 km (16 mi) south-west of Piaseczno, and 36 km (22 mi) south-west of Warsaw.