Permanent magnet (PM) synchronous motors have found numerous applications over the last two decades due to their high torque to weight ratio and efficiency. However, one of the main drawbacks of the PM motors is the magnet corrosion. This paper investigates the influence of magnet corrosion on the performance of surface mounted permanent magnet motors. Uncorroded and corroded magnet rotors are used to investigate the motor performance including voltage and torque constants. It has been found out that the corroded rotor does not degrade the motor performance even after the intense corrosion tests if good quality NdFeB magnets are used.