Organic acidurias are congenital errors of the intermediate metabolism caused by a specific metabolic defect which gives rise to an anomalous excretion of carboxilic acids. The majority of these disease appear in the first weeks of life with few specific symptoms as hypotonia, lethargy, coma, seizures, vomits and dehydration. From biochemical point of view the findings of metabolic acidosis, ketosis, and hyperamoniemia are common. Frequently clinical symptoms are precipitated by infectious disease, traumatism or stress situations. The treatment applied in the initial phases may be efficient; for this reason diagnostic and early treatment are necessary for avoid irreversible sequelae. The diagnosis is also important for posterior genetic counseling. Organic acidurias are an interesting field of work for the pediatrician, neuropediatrician, biochemist and dietician to offer new perspectives in the diagnosis and treatment of many congenital errors of the metabolism.