From April 1974 to February 1985 131 patients were operated for reconstruction of the right ventricular outflow tract with 147 valve-carrying conduits. 79 were xenogenic (XC) and 68 sterilized and preserved allogenic (AC) conduits between right heart and lung in the following heart defects: DOLV 2, DORV 6, Fallot 24, pulmonary atresia 33, TGA, VSD and pulmonic stenosis 20, single ventricle 7, tricuspid atresia 10 and truncus arteriosus 41. Mean age was 6.6 and 5.2 years of age. The operative mortality was 13.6%. 11 more patients died later--2.0 months to 2.5 years postoperatively. 16 patients were reoperated (change of the conduit). The observation time is now 5 years in the XC-group and 1.4 years in the AC series. Up to now no dysfunction in the AC-group could be seen.