Repair of an atrioventricular septal defect was performed in 134 patients from 1973 to 1985. Interventricular communication was present in 54 (40%) and none was present in 80 (60%). There were 12 hospital deaths (9%; 70% confidence limits 6%-12%). Earlier date of operation (p = 0.03) and younger age at repair (p = 0.005) were incremental risk factors for hospital death after repair of partial atrioventricular septal defect. Smaller size (p = 0.003) and longer cross-clamp time (p = 0.002) were risk factors for hospital death in those patients with complete atrioventricular septal defect. Higher preoperative pulmonary vascular resistance was a risk factor for death in both groups (p = 0.007). The 10 year actuarial survival rate was 82% overall. Increasing preoperative severity of left atrioventricular valve incompetence was not a risk factor for early (p = 0.001) or late (p = 0.002) death. The 10 year actuarial freedom from reoperation after repair of partial atrioventricular defects was 85%, and it was 68% for complete atrioventricular defects (p = 0.06). We conclude that the intermediate term results after repair of atrioventricular septal defects are good. Incompetence of the left atrioventricular valve has apparently been neutralized as a risk factor for hospital death in this series. However, the durability of the repair has been disappointing. A policy of earlier repair has been adopted and should improve hospital mortality and permit better preservation of the atrioventricular valve structures with resultant improved late term functional status.