The electrical impedance of the isolated frog skin has been measured in the frequency range 0.05 Hz-2 kHz. Under certain conditions, the resistance and capacitance of both outward-facing and inward-facing membranes can be estimated from these measurements. The inner membrane has a capacitance which is some 50 times greater than that of the outer membrane; the ratio of membrane areas is likely to have a similar value. The large area of the inner membrane would be explained if the interiors of all living cells in the epithelium were in electrical contact. With Ringer solution bathing both sides of the skin, the resistance of the inner membrane is much smaller than that of the outer membrane.