Stary Cydzyn [ˈstarɨ ˈt͡sɨd͡zɨn] is a village in the administrative district of Gmina Piątnica, within Łomża County, Podlaskie Voivodeship, in north-eastern Poland. It lies approximately 6 kilometres (4 mi) north of Piątnica, 9 km (6 mi) north of Łomża, and 72 km (45 mi) west of the regional capital Białystok.