Recently a number of defects of fatty acid transport and beta-oxidation have been described. Primary carnitine deficiency presents itself as muscle carnitine deficiency, systemic carnitine deficiency or a cardiomyopathic subtype. Another abnormality of fatty acid transport is due to inner carnitine palmitoyl transferase deficiency, usually associated with a myoglobinuric phenotype. Long chain, medium and short chain acyl-CoA-dehydrogenase defects are usually associated to Reye's syndrome, encephalopathy, organic aciduria and secondary carnitine deficiency.