Gostynin County (Polish: powiat gostyniński) is a unit of territorial administration and local government (powiat) in Masovian Voivodeship, east-central Poland. 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 Gostynin, which lies 107 kilometres (66 mi) west of Warsaw. The county covers an area of 615.56 square kilometres (237.7 sq mi). As of 2019 its total population is 43,099, out of which the population of Gostynin is 18,588, and the rural population is 24,511.