Przasnysz County (Polish: powiat przasnyski) is a unit of territorial administration and local government (powiat) in Masovian Voivodeship, east-central Poland.

It came into being on 1 January 1999, as a result of the Polish local government reforms passed in 1998.

Its administrative seat and largest town is Przasnysz, which lies 90 kilometres (56 mi) north of Warsaw.

The only other town in the county is Chorzele, lying 26 km (16 mi) north of Przasnysz.

The county covers an area of 1,217.82 square kilometres (470.2 sq mi).