Sierpc County () 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 only town is Sierpc, which lies north-west of Warsaw.
The county covers an area of . As of 2019 its total population is 52,077, out of which the population of Sierpc is 17,994, and the rural population is 34,083.
Sierpc County is bordered by à »uromin County to the north-east, Pà Âoà Âsk County to the east, Pà Âock County to the south, Lipno County to the west and Rypin County to the north-west.
The county is subdivided into seven gminas (one urban and six rural). These are listed in the following table, in descending order of population.
<br>