The resistance and capacitance of the isolated amphibian skin have been determined from measurements of the response of the voltage across the skin to small steps to current. Previous work indicates that the electrical impedance of frog skin, when the skin is bathed with Ringer's solution on both sides, is largely determined by the properties of the functional outward-facing membrane of the skin, the outer membrane of the stratum granulosum (P.G. Smith, 1971, Acta Physiol. Scand. 81:355). This membrane can be represented by a resistance and capacitance in parallel. Aldosterone, which induces conversion of the s. granulosum into a cornified cell layer and transformation of the cell layer below into a new s. granulosum, also causes a transient rise in resistance and a short-lived decrease in capacitance to about one-half its initial value. It is suggested that these electrical changes are caused by the transitory presence of two functional outward-facing membranes in series. The method of determining resistance and capacitance from the voltage response is discussed in the Appendix.