Abstract Cerebral adrenoleukodystrophy (ALD) and adrenomyeloneuropathy (AMN) are the two most frequent clinical phenotypes of the same genetic defect leading to the accumulation of very long chain fatty acids (VLCFA). Previous studies have suggested that inflammatory cytokines may play a role in the cerebral demyelination and in phenotype expression of the disease. We analyzed cytokine production by stimulated peripheral blood mononuclear cells (PBMC) from 17 patients (four asymptomatic subjects, eight AMN and five ALD). Our results show that lipopolysaccarides (LPS) stimulated PBMC from both symptomatic and asymptomatic patients have an increased production of IL-12 and TNFα compared to controls, while after phitoemoagglutinin (PHA) stimulation we observed a decreased production of IL-6 and IL-10. These data indicate that, following an immunological stimulus, PBMC from patients have an increased production of cytokines typical of a Th1 cell response which is able to promote the inflammatory process. This characteristic profile of cytokine production could be related to the biochemical defect and could have a role in central nervous system (CNS) pathogenesis.