Over the past 15 years 23 patients, aged 14-50, with aortic sinus-cardiac chamber fistulous communication have been operated upon. All were symptomatic and had angiographic evaluation before surgery. The last 5 were diagnosed by two-dimensional echocardiography. The origin of the fistula was the right aortic sinus in 22 and the non-coronary sinus in 1. The involved cardiac chamber was the right ventricle in 18, right atrium in 3 and left ventricle in 2. Associated lesions were ventricular septal defect (VSD) in 9, ventricular septal defect+atrial septal defect (VSD+ASD) in 1, ventricular septal defect+pulmonary stenosis (VSD+PS) in 1, atrial septal defect (ASD) in 3 and congenital aortic stenosis (AS) in 1. At surgery both the aorta and involved cardiac chamber were opened. No recurrence was encountered when the fistula was repaired using teflon felts on both ends. Three patients, 2 of whom had been operated upon before the use of cardioplegic arrest, died (13%).