A 19-year-old patient presented with spastic paraparesis and peripheral neuropathy without clinical or biochemical signs of adrenal insufficiency. The diagnosis of adrenomyeloneuropathy was supported by typical ultrastructural findings in peripheral nerve and endomysial nerve bundles and by a positive family history. Indeed his younger brother died at age 12 from a demyelinating disease of the central nervous system. Cutaneous nerve bundles and postmortem examination limited to the brain demonstrated features specific for adrenoleukodystrophy. The various features of both disorders are discussed. Their occurrence in the same sibship pleads strongly for a very close relationship.