The recent use of electric motors for vehicle propulsion has stimulated the development of numerical methodologies to predict their noise and vibration behavior. These simulations generally use models based on an ideal electric motor.But sometimes acceleration and noise measurements on electric motors show unexpected harmonics that can generate acoustic issues. These harmonics are mainly due to the deviation of the manufactured parts from the nominal dimensions of the ideal machine.The rotor eccentricities are one of these deviations with an impact on acoustics of electric motors. Thus, the measurement of the rotor eccentricity becomes relevant to understand the phenomenon, quantify the deviation and then to use this data as an input in the numerical models.An innovative measurement method of rotor eccentricities using fiber optic displacement sensors is proposed. These sensors have the characteristics to get round the difficulties of such a measurement: small size, adaptive shape and insensitivity to magnetic and electric perturbation.The measurement of rotor eccentricities is performed on an automotive electric motor in operating conditions in a test bench. The associated preparation work and the precaution are also detailed. Then, the measured data including rotor orbits are analyzed. Finally, the links with the other data measured such as stator acceleration levels and stator deflection shapes are established.