Small cryopreserved allografts for use in neonates and infants are increasingly difficult to find. We describe a technique for surgically reducing the size of the more readily available large-diameter allografts to make them conform to size requirements appropriate for neonates and infants. This technique involves a longitudinal incision of the allograft from its muscular annulus to its distal orifice with the excision of a single valve leaflet. The two commissural posts of the excised leaflet and the wall of the allograft are then reapproximated with fine suture. Four patients ranging in age from 14 days to 11 months (mean age, 5.2 months) and ranging in weight from 3 to 8.4 kg (mean weight, 5.2 kg) underwent reconstruction of the right ventricular outflow tract using this surgical technique. Two patients underwent repair of truncus arteriosus (age, 14 days and 16 days) and two patients underwent Rastelli operations (age, 9 months and 11 months). The mean follow-up time was 22.5 months (range, 14 to 28 months). All 4 patients are alive and well. One patient requires digoxin and furosemide for moderate quadricuspid truncal valve insufficiency. Serial echocardiography documents mild allograft stenosis in 2 patients and trivial to mild allograft insufficiency in 2 patients. Because handling characteristics and lower bleeding risks render allograft conduits preferable to synthetic conduits and, furthermore, because conduit insertion of any type in the neonate will eventually be outgrown and require replacement, we find this technique to be justifiable as a therapeutic option. In the short term, the technique results in excellent functional results and provides an alternative to synthetic conduits when an appropriate sized allograft is unavailable.