Peroxisome biogenesis factor 10 (PEX10) is involved in the import of peroxisomal matrix proteins, and the mutation of this gene causes 3 subtypes of peroxisome biogenesis disorders, namely Zellweger syndrome (severe), neonatal adrenoleukodystrophy (moderate) and an ataxic form (mild). Here, we report 3 siblings of the ataxic form with cerebellar ataxia, mild mental retardation, and 3 additional characteristic features: mydriasis, hyperreflexia and involuntary head movement. All 3 siblings are compound heterozygous for a previously reported mutation, c.2T > C (p.M1T), and a novel mutation, c.920G > A, causing a missense change (p.C307Y) located in the RING finger domain of PEX10. The present cases suggest that these PEX10 mutations involve not only cerebellar but also more multiple nervous systems including pupillary autonomic, pyramidal and extrapyramidal systems.