Metabolic function of peroxisomes includes oxidation of wide spectrum of substances in the presence of oxygen. Hydrogen peroxide formed at the same time is either degraded by catalase or further utilized in peroxidative reactions. From the view of cellular pathology, the most important becomes alpha and beta-oxidation of carboxylic acids, particularly beta-oxidation of long-chain carboxylic acids, which undergoes selectively in peroxisomes. Mutations of peroxisomal genes result in serious metabolic disorders. At present about twenty hereditary peroxisomal diseases has been described. One group of them includes generalized forms (impairment of peroxisome biogenesis); diseases of other group result from isolated defects of individual peroxisomal enzymes. Combined incidence of peroxisomal hereditary disorders in the Western Europe is estimated to be 1:10 000. Beside the X-linked adrenoleukodystrophy, all others have the autosomal-recessive type of heredity. In phenotypic manifestation of generalized forms, as in the Zellweger syndrome, neonatal adrenoleukodystrophy, infantile Refsum disease, rhizomelic chondrodysplasia pun- ctata, an impairment of the central nervous system, liver, and kidney dominate. Most of the patients die within one year, survival period longer than three years becomes exceptional. X-adrenoleukodystrophy, pseudoneonatal adrenoleukodystrophy, trifunctional enzyme deficiency, Refsum disease, primary hyperoxaluria, acatalasemia result from the deficiency of a single enzyme. The most frequent peroxiosomal hereditary disease, the X-adrenoleukodys- trophy, has several clinical phenotypes, which most frequently manifest already in infants. The disease has also a clinically less serious form, which manifest only in adults – the adrenomyeloneuropathy. For the postnatal but also for the prenatal diagnostics, methods of biochemistry, molecular genetics, morphology, and immunocytochemistry are necessary.

        Key words: peroxisomes, beta-oxidation, metabolic functions of peroxisomes, peroxisomal hereditary disorders, Zellweger syndrome, adrenoleukodystrophy, Refsum disease.