Abstract: A return electrode monitoring system for use with a patient return electrode adapted for contacting a patient, the return electrode having two, spaced apart conductors attached thereto for connecting the electrode to a generator of electrosurgical current which passes through the electrode, the system comprising means for applying a monitoring current through the conductors to the electrode; detecting means responsive to the monitoring current for producing a signal which is a function of the impedance between the two conductors, the detecting means including means for substantially eliminating any effect the electrosurgical current might have on the production of the signal when the generator is operational and the patient is in contact with the electrode; means for establishing a desired range having at least an upper limit for the impedance; and determining means responsive to the signal for determining whether the impedance is within the desired range.