Six to thirty percent of right ventricular-to-pulmonary arterial (RV-PA) valved conduits in children fail within 5 years. Experience with correction of tetralogy of Fallot has shown that a competent pulmonary valve is not essential for excellent late results in most patients. Between March 1980 and November 1984, 26 patients who were 12.5 +/- 3.3 years old underwent conduit replacement 6.7 +/- 2.4 years after definitive repair of congenital heart defects in which a xenograft RV-PA valved conduit had been used. A new Dacron tube graft (n = 15) or pericardial (n = 8), dura mater (n = 2), or Dacron patch (n = 1) over the previous conduit bed was used as replacement. Preoperative mean right ventricular systolic pressure was 90.5 +/- 20 mm Hg and mean gradient across the conduit was 67.9 +/- 24.5 mm Hg. After replacement with a nonvalved conduit, right ventricular systolic pressure was reduced to 45.2 +/- 10.8 mm Hg (p less than .001), with a gradient of 8.9 +/- 7.6 mm Hg (p less than .001). There were no operative deaths. Follow-up at 19.5 +/- 14.9 months (range = 0 to 53) showed that all patients were in New York Heart Association class I (n = 21) or class II (n = 5). In the absence of pulmonary hypertension, hypoplastic pulmonary arteries, significant right ventricular dysfunction, or unrepaired tricuspid regurgitation, replacement of an obstructed conduit with a nonvalved conduit gives excellent early results and may diminish the need for late reoperation.