Grójec County (Polish: powiat grójecki) 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 largest town is Grójec, which lies 40 kilometres (25 mi) south of Warsaw. The county contains three other towns: Warka, 25 km (16 mi) east of Grójec, Nowe Miasto nad Pilicą, 34 km (21 mi) south-west of Grójec, and Mogielnica, 22 km (14 mi) south-west of Grójec.