Eight patients with aneurysms of the right ventricular outflow tract patch following tetralogy of Fallot repair were found to have residual distal obstructions. The site of such an obstruction must be carefully documented preoperatively because failure to relieve significant distal obstruction may result in recurrent aneurysm formation. Chest radiography; echocardiography, including Doppler analysis; and cardiac catheterization, including angiocardiography, each have a role in the detection and evaluation of this complication.