The peroxisomal disorders represent a group of inherited diseases in man in which there is an impairment in one or more peroxisomal functions. The disorders known up to now are usually subdivided into three groups depending upon whether there is a more generalized, multiple or single loss of peroxisomal functions. In this paper we will briefly describe the peroxisomal disorders known thus far with the biochemical abnormalities identified. Furthermore, we will describe a straightforward approach for the postnatal identification of patients suspected to suffer from a peroxisomal disorder which is of great importance since reliable prenatal diagnostic methods have become available for each of these disorders.