Potential for electromagnetic interference (EMI) with cardiac pacemakers in workplaces in electric utilities due to 50-and 60-Hz fields is well known. Only younger employees of electric-utility companies may want to return to their jobs that often entail exposure to such fields. EMI may occur due to exposure to strong external electric fields, magnetic fields, contact currents, and electrostatic discharges (ESD). Numerical modeling of the potential differences produced between the pacemaker electrodes in situ, i.e., in the heterogeneous model of a human body, allows for the evaluation of potential EMI prior to an implantation of the device. Such modeling has been performed and the results are presented and compared for different conditions of potential EMI. As expected, unipolar pacemakers are more susceptible than bipolar devices.Index Terms-Electromagnetic interference (EMI), pacemakers, power line frequency.