Mścichy [ˈmɕt͡ɕixɨ] is a village in the administrative district of Gmina Radziłów, within Grajewo County, Podlaskie Voivodeship, in north-eastern Poland. It lies approximately 6 kilometres (4 mi) north-east of Radziłów, 25 km (16 mi) south of Grajewo, and 58 km (36 mi) north-west of the regional capital Białystok.