Clinical and sural nerve biopsy findings in two brothers and their mother affected by adrenomyeloneuropathy/adrenoleukodystrophy (AMN/ALD) illustrate the variability of histopathological changes in this disorder. The number of diagnostic inclusions, i.e., trilaminar leaflets, varied considerably from case to case and showed no correlation to the extent of neurological symptoms. In addition, mitochondrial abnormalities (granular and filamentous inclusions and abnormal cristae), which have not previously been described in AMN/ALD, were detected. These alterations could be secondary to the peroxisomal defect and the increased amount of very long chain fatty acids or could be caused by a more generalized defect.