Aortopulmonary window coexisting with tetralogy of Fallot (TF) was prospectively diagnosed by two-dimensional (2D) echocardiography and Doppler in an 18-month-old boy; the diagnosis was confirmed by cardiac catheterization and angiocardiography. Surgical correction was performed, but the patient died in the operating room from right ventricular dysfunction. The autopsy showed an adequate surgical repair, but the histologic examination of the lungs demonstrated severe pulmonary vascular disease, which was presumed to be the cause of death.