Clinical morphological, biochemical, radiological, and neurophysiological findings in disorders characterized by storage of very long chain fatty acids are reviewed. The dynamics of clinical symptomatology and neuropathological changes are different in adrenoleukodystrophy and adrenomyeloneuropathy. The observation of both and of intermediate conditions within families suggests a continuum of disease states caused by a single error of metabolism with sex-linked recessive transmission. Though the basic metabolic defect is still unknown, identification of heterozygote carriers and prenatal diagnosis is possible by determination of very long chain fatty acids in fibroblasts. Therapeutic trials have so far been unsuccessful. The neonatal form of andrenoleukodystrophy appears to be a distinct genetic entity with autosomal recessive transmission.