Sejny County a unit of territorial administration and local government (powiat) in Podlaskie Voivodeship, in the extreme north-east of Poland, on the border with Lithuania and Belarus. It came into being on January 1, 1999, as a result of the Polish local government reforms passed in 1998. Its administrative seat and only town is Sejny, which lies 112 kilometres (70 mi) north of the regional capital Białystok.