This study has shown that the apparent impedance of both electrode-electrolyte interfaces is small at the current levels used for transchest ventricular defibrillation, making it clear that the appearent impedance appearing between the electrode terminals is largely that of the subject. In addition, it has been shown that for measurement of the impedance of the subject, with low-intensity sinusoidal current, the electrode-electrolyte impedance becomes negligible above 10 kHz and is only slightly affected by the magnitude of the current used to make the measurement.