Olszewo [ɔlˈʂɛvɔ] is a village in the administrative district of Gmina Śniadowo, within Łomża County, Podlaskie Voivodeship, in north-eastern Poland. It lies approximately 4 kilometres (2 mi) north-east of Śniadowo, 14 km (9 mi) south of Łomża, and 77 km (48 mi) west of the regional capital Białystok.