The rhizomelic type of chondrodysplasia punctata (RCDP) is recognizable at birth because of the typical phenotype and radiological features. Most patients die young, some survive until their teens but all are severely retarded. Recent studies showed RCDP to be a peroxisomal disorder. Peroxisomal investigations may be important in defining the prognosis for an individual patient, and are definitely of use in antenatal diagnosis.