Glutaric aciduria type I is an autosomal recessive disorder resulting from a deficiency of glutaryl-CoA dehydrogenase. This leads to an accumulation of glutaric and 3-hydroxyglutaric acids and secondary carnitine deficiency. The symptomatology is discussed, especially those resulting from lesions in the basal ganglia, and the encephalopathic episodes which are often precipitated by infections. The variability of the clinical presentation is stressed. The most serious complications are collections of fluid and blood in the middle fossae, the bleeding resulting from rupture of bridging veins. The prognosis does not seem to be related to the extent of the enzyme deficiency. The diagnosis is confirmed by identifying the abnormal acids in the urine and the deficiency of the enzyme in cultured fibroblasts. The differential diagnosis is reviewed: from other biochemical disorders and from other cerebral lesions. Treatment is by special diet and carnitine supplementation. The dystonia can prove difficult to treat, and surgery may be needed to remove the collections of fluid and blood. Glutaric aciduria type II is caused by a deficiency of either electron transport flavoprotein or of electron transport flavoprotein oxoreductase. The symptoms can be mild or severe. The former may only occur in times of stress, and the latter include congenital anomalies, especially of the kidneys and heart. The pathology of these are discussed. The demonstration of organic acids in the urine and the results of muscle and liver biopsies confirm the diagnosis, and treatment with a special diet and supplementation with carnitine and riboflavine is effective.