The main objective of this paper is to put the different conditions which verify the eccentricity fault in induction motors (IMs). Many harmonic types are exists in the stator current spectrum in healthy or in faulty IMs. In addition, there is a big problem about the overlap between several harmonics. Among these harmonic types: the rotor slot harmonics (RSHs), saturation harmonics (SHs), magneto motive force harmonics (MMFHs), fault harmonics, etc. So, we have tied to analyze the spectral content of the stator current in order to verify some harmonic exists. In addition, it is known that the generation of some harmonics is not possible for all machine types. Many researchers have shown that the existence of these harmonics in the stator current spectrum depends on the pole pair numbers and the rotor slot numbers of the IM. This study tried to put the conditions that verify the existence of the rotor eccentricity fault in IM types. Finally, our verification based on the experimental results of the IMs under healthy and faulty state.