Rżaniec [ˈrʐaɲɛt͡s] is a village in the administrative district of Gmina Olszewo-Borki, within Ostrołęka County, Masovian Voivodeship, in east-central Poland. It lies approximately 18 kilometres (11 mi) west of Ostrołęka and 101 km (63 mi) north of Warsaw.