Between August 1982 and December 1986, 56 patients survived implantation of an extracardiac valved conduit for complex congenital heart disease. The mean age at operation was 4.2 years (16 days to 24 yrs) and the mean weight was 15.9 kg (2.4 to 93.0 kg). The diagnosis was pulmonary atresia (PA) with ventricular septal defect (VSD) in 13 patients, tetralogy of Fallot in 11, transposition of the great arteries (TGA) with VSD in 8, truncus arteriosus, in 7, complex left ventricular outflow tract obstruction (LVOTO) in 6, complex left atrioventricular valve obstruction in 4, double outlet right ventricle with VSD and subaortic obstruction in 3, univentricular heart with pulmonary stenosis in 2, TGA with LVOTO in 1, and PA with intact ventricular septum in 1. In 35 patients, a preclotted conventional Dacron conduit (CDC) with bioprosthetic valve was used, in 19 patients a collagen-sealed Tascon valved conduit (TC) was implanted, and in 1 patient an aortic homograft was used. In a mean follow-up of 32.5 months (9 to 64 mo), there were two deaths (2/56, 3.6%) that were not related to the conduit. All survivors have been evaluated by two-dimensional and Doppler echocardiography, and 29/56 (51.8%) underwent cardiac catheterization. Nine patients (9/56, 16.1%) underwent successful valved conduit replacement, in seven cases with a nonvalved conduit. There was a significant difference (P = .011) with regard to the incidence of conduit replacement between the group with CDC (2/36, 5.5%) and the group with TC (7/19, 36.8%). Five patients underwent percutaneous transluminal balloon dilatation of the prosthetic conduit, with adequate relief of the gradient in four patients.(ABSTRACT TRUNCATED AT 250 WORDS)