In the past few years, the smart grids have attracted more and more attention. The fact that these systems are based on the pervasive use of new Information and Communications Technologies (ICTs) opens new perspectives in an aim to improve the electrical grid performances. One of the most commonly deployed technologies in such a real environment is the Wireless Sensor Networks (WSNs) technology. WSNs are thus used to monitor and control the electrical grid components. In this paper, the authors will give an overview on WSNs applications and challenges for smart grids.