Inherited via the X chromosome, adrenomyeloneuropathy is a rare cause of primary adrenocortical insufficiency. Neurological signs are of central and peripheral demyelinization, while endocrinologically it is characterized by Addison's disease and primary testicular insufficiency. In two patients with this condition the metabolic defect in the breakdown of long-chain fatty acids was confirmed by an increased hexakosan (C 26) blood level. One patient had an isolated failure of the zona fasciculata; in the other there was clinically manifest complete adrenocortical insufficiency. Both patients had incipient hypogonadism. In the second case, neurological symptoms preceded the endocrinological ones, while in the first both the family history and the adrenocortical insufficiency led to the diagnosis. In peripheral neuropathy in a young male, attention should always be given to signs of incipient adrenocortical insufficiency.