Siemień Nadrzeczny [ˈɕɛmjɛɲ naˈdʐɛt͡ʂnɨ] is a village in the administrative district of Gmina Łomża, within Łomża County, Podlaskie Voivodeship, in north-eastern Poland. It lies approximately 7 kilometres (4 mi) south-east of Łomża and 67 km (42 mi) west of the regional capital Białystok.