Sianno [ˈɕannɔ] is a village in the administrative district of Gmina Brochów, within Sochaczew County, Masovian Voivodeship, in east-central Poland. It lies approximately 4 kilometres (2 mi) east of Brochów, 12 km (7 mi) north-east of Sochaczew, and 49 km (30 mi) west of Warsaw.