SUMMARYMeasurement of the resting electrical potential difference on the surface of the skin has been made on patients with suspected basal cell carcinoma. It was demonstrated that in fifty‐five lesions from fortynine patients, the mean electrical potential difference from thirty‐six basal cell carcinomas was found to be +11 mV, from nineteen benign inflammatory lesions it was found to be +2 mV, and from normal skin, contra‐lateral to the lesions in both groups, it was found to be −3 mV. All the measurements are relative to a reference electrode placed under the tongue. The difference between the means for the inflammatory lesions and for the normal skin was found to be statistically insignificant, but the difference between these means and the mean potential difference for the basal cell carcinoma group was found to be highly significant (P<0.1%). However, the populations overlap to such an extent as to make the measurement, in its present form, useless as a diagnostic te