X-linked adrenoleukodystrophy (X-ALD) is an inherited disorder of peroxisomal beta-oxidation associated with accumulation of saturated very long-chain fatty acids, which results in central and peripheral demyelination and in impaired function of adrenal cortex and testes. The phenotypic expression is highly variable, childhood cerebral ALD (CCALD) and adrenomyeloneuropathy (AMN) being the main variants. We explored the 30 Dutch kindreds well known to the Dutch X-ALD/AMN Study Group and phenotyped 77 male patients: 35 (46%) had AMN and 24 (31%) CCALD or adolescent cerebral ALD (AdolCALD). These percentages differ significantly from previous reports, in which 25 to 28% of the patients developed AMN and 53 to 57% CCALD or AdolCALD. Our findings indicate that--at least in the Netherlands--AMN may be the most frequent phenotype of X-ALD.