The peroxisomal disorders represent a group of inherited metabolic disorders that derive from defects of peroxisomal biogenesis and/or from dysfunction of single or multiple peroxisomal enzymes. Because peroxisomes are involved in the metabolism of lipids critical to the functioning of the nervous system, many of the peroxisomal disorders manifest with significant degrees of progressive psychomotor dysfunction. These disorders should be considered in the differential diagnosis of the infant with hypotonia and psychomotor delay (especially if accompanied by facial dysmorphisms, hepatomegaly, cataracts and/or retinitis, calcific stippling, short limbs, or combinations of these features), in the school-aged child with progressive neurologic dysfunction, and in adults with slowly progressive motor dysfunction. Current knowledge of peroxisomal biochemical and enzymatic processes permits precise identification of particular disorders within the peroxisomal disorder grouping. An effort should be made to identify the specific peroxisomal disorder to provide a precise explanation for neurodevelopmental deficits, to potentially prevent recurrence through genetic counseling, and to provide appropriate therapies when available.