We report the measurement of transepithelial voltage across the nasal epithelium in a neonate with pseudohypoaldosteronism (PHA) type 1. A 5-day-old infant was seen with hyponatremia, hyperkalemia, and elevated plasma renin and aldosterone levels. Sweat Cl(-) concentration was also increased. Measurements of voltage showed a basal value of zero and the absence of an amiloride-sensitive voltage. However, voltage changed as expected for normal cyclic adenosine monophosphate-stimulated Cl(-) transport. These data demonstrate the absence of amiloride-sensitive Na(+) transport across airway epithelia in a neonate with PHA. The findings suggest that measurements of voltage could be of value in the diagnosis of PHA.