Peroxisomal acyl-coenzyme A oxidase deficiency (formerly also called pseudoneonatal adrenoleucodystrophy) is a disorder of peroxisomal fatty acid oxidation with a severe presentation. Most patients present at birth or in early infancy, and the mean age of death was 5 years in a recently published cohort of 22 patients. Brain imaging shows a progressive leucodystrophy. The authors report here the first adult patients (two siblings, 52 and 55 years old) with peroxisomal acyl-coenzyme A oxidase deficiency with a remarkably mild clinical presentation. Magnetic resonance brain imaging revealed profound atrophy of the brainstem and cerebellum.