Abstract: In this study, we approach the diagnosis of the stator and rotor defects in the asynchronous squirrel-cage machines. After having evoked the principal defects being able to occur, we propose a model of the machine based on the method of circuits magnetically coupled. This model makes it possible to study the influence of the defect of short circuit and break of bar, on the general behavior of the asynchronous motor. In complement of the undertaken study, we will highlight the importance of the analysis of the signals for the diagnosis of the stator and rotor defects.