A four-month-old boy with beta-ketothiolase deficiency is described in this report. Presenting symptoms and signs were vomiting, irritability and acidotic respiration. Laboratory investigations revealed hyperglycinemia, metabolic acidosis and ketosis. Subsequent urinary GC-MS analysis of the patient's urine sample showed the typical pattern of beta-ketothiolase deficiency. Our experience with this case indicates that accurate diagnosis and early treatment of inborn errors might be lifesaving.