Between January 1985 and October 1998, 169 of 372 patients who underwent a modified Fontan procedure had atrioventricular valve regurgitation (AVVR) that ranged in degrees from 1 to 4. Concomitant repair for AVVR was performed in the majority of cases. All but 12 patients had the AV valve repaired, mainly by circular annuloplasty; none had valve replacement. Although mortality was significantly higher in the AVVR cases (21 of 169 [12%]) than in the cases without AVVR (eight of 203 [3.9%]; P <.007, chi-square), actuarial survival in the AVVR cases was 83% at 5 years, 81% at 10 years, and 73% at 12 years. The degree of AVVR before surgery was 1.62 +/- 0.73 on average; 82 cases had more than grade 2 regurgitation. There was a significant decrease to 0.54 +/- 0.61 (P <.0001) after surgery in long-term survivors. Cases with AVVR can be treated with reasonable risk provided proper repair of the valve is performed. Circular annuloplasty is a simple and uniformly effective method with which to control regurgitation, even for the common AV valve. Copyright 1999 by W.B. Saunders Company