Monitoring and controlling of electric power losses have high importance in any power distribution utility, since reducing system loss is one of its main objectives. System loss is a combination of technical and non-technical loss. Current practices suggest using different technical devices such as appropriate-size transformer and low voltage capacitor in controlling the technical losses, however, it is impossible to control the non-technical losses using such devices because it happens as a result of actions external to the power system (e.g. meter inaccuracies and/or power theft). Statistical Process Control (SPC) tools are being used broadly in areas outside the manufacturing industries in recent years since they showed their effectiveness in continuous monitoring and improvement. In this study, X&MR control chart is used for monitoring power losses through transmission and distribution system. The concept is discussed and illustrated through a case study. The results of the study show that the SPC chart is able to detect the unusual power losses successfully.