A patient with tetralogy of Fallot associated with aortopulmonary window has been documented. The association was found in one case out of 350 consecutive cases of Fallot's tetralogy evaluated cineangiographically. Since tetralogy of Fallot may be completely masked by the aortopulmonary window it is suggested that a right ventricular angiogram should be obtained in all patients with an aortopulmonary window.