A current leakage control circuit regulates the output power of an electrosurgical generator to limit the amount of leakage current. The leakage current is monitored with a differential transformer which has the output and return leads of the electrosurgical generator as first and second windings. A third or sense winding produces a control signal whenever the currents in the output and return leads are not equal, thus indicating current leakage. The control signal is compared to a predetermined maximum safe level of leakage current. If this predetermined level is exceeded, a power control feedback loop of the electrosurgical generator reduces the output power to a sufficiently lower level to reduce the leakage current within a maximum acceptable limit.