Udrzynek [uˈdʐɨnɛk] is a village in the administrative district of Gmina Brańszczyk, within Wyszków County, Masovian Voivodeship, in east-central Poland. It lies approximately 7 kilometres (4 mi) north-east of Brańszczyk, 18 km (11 mi) north-east of Wyszków, and 69 km (43 mi) north-east of Warsaw.