The electrical energy generation companies are always tried to improve the system performance through reducing the active power losses and that lead the fuel cost to be reduced too. One of the ways is by incorporating Distributed Generation (DGs). DGs are becoming more prominent in transmission systems due to the increasing demand for the electrical energy and their location will have an impact on the network system losses. This article discusses the application of Sensitivity Analysis (SA) to improve power losses when DGs are used. By substituting these losses sensitivities, the optimal DGs location for minimizing the system losses can be directly obtained. The simulation results on IEEE 30 bus test system indicate that bus 13 is the optimal location of DG based on its negative of partial derivative value.