A case of a month-old baby admitted for dyspnea and cyanosis, is described. His past history consisted of only mild cyanosis during crying. On physical examination nail beds and lips were cyanotic; on heart auscultation the pulmonary second sound was single. The chest X-ray showed a decreased pulmonary vascularity; the ECG demonstrated extreme right axis deviation (-170°). Capillary gas analysis revealed hypoxic metabolic acidosis. Ten hours after his admission the child suddenly died. The anatomicopathological examination stated the diagnosis of double outlet right ventricle (DORV), infundibular pulmonary stenosis and common atrioventricular canal (transitional type). When clinical findings are compatible with DORV the ECG could be of value in establishing the presence of common atrioventricular canal when extreme right axis deviation is found.