ABSTRACTPalmar skin potential levels (SPLs) and the amplitude of the T‐wave of the electrocardiogram (EKG) were measured in groups of habituated male subjects in conditions of bed rest and while resting in a sitting position. Significant correlations of ‐.70 and ‐.61 between the negativity of SPL and T‐wave amplitude were obtained when there was minimal palmar sudorific activity and skin potential could be designated as ‘basal’ (BSPL). Previous work had suggested that BSPL might be related to extracellular potassium (K+) levels and evidence is presented which relates EKG T‐wave amplitude to palmar K+ levels. The results thus provide support for the hypothesis that measured values of SPL reflect levels of body K+.