Pseudohypoaldosteronism is a rare inherited disease characterized by renal salt loss, hyperkalemia and metabolic acidosis despite highly elevated aldosterone values. We previously reported absent or reduced numbers of mineralocorticoid receptors in mononuclear leukocytes and defective effector mechanism as shown by no response in vitro to the incubation of aldosterone in terms of intracellular electrolyte content. We have studied the inheritance of this disorder in ten families and found two different kinds of inheritance: autosomal recessive--often in interrelated families--and autosomal dominant in unrelated families. Parallel studies in the families with the autosomal dominant form of inheritance demonstrated in addition that the effector mechanism of aldosterone is impaired in vitro both in the affected patients and in the carrier relatives characterized by a low number of mineralocorticoid receptors.