Sianno
{{for|the town in Belarus|Syanno}}
{{Infobox settlement
| name = Sianno
| settlement_type = Village
| total_type =
| image_skyline =
| image_caption =
| image_flag =
| image_shield =
| image_map =
| subdivision_type = Country
| subdivision_name = {{POL}}
| subdivision_type1 = Voivodeship
| subdivision_name1 = Masovian
| subdivision_type2 = County
| subdivision_name2 = Sochaczew
| subdivision_type3 = Gmina
| subdivision_name3 = Brochów
| coordinates = {{coord|52|19|6|N|20|18|37|E|region:PL|display=title,inline}}
| pushpin_map = Poland
| pushpin_label_position = bottom
| elevation_m =
| population_total = 81
| website =
}}
Sianno {{IPAc-pl|'|ś|a|n|n|o}} is a village in the administrative district of Gmina Brochów, within Sochaczew County, Masovian Voivodeship, in east-central Poland.{{TERYT}} It lies approximately {{convert|4|km|mi|0|abbr=on}} east of Brochów, {{convert|12|km|mi|0|abbr=on}} north-east of Sochaczew, and {{convert|49|km|mi|0|abbr=on}} west of Warsaw.