Background: The fate of the truncal valve (TV) after truncus arteriosus repair remains poorly defined. The purpose of this report was to analyze how the TV influences outcome of truncus arteriosus repair. Methods: From January 1986 to December 2003, 153 patients underwent complete repair of the truncus arteriosus. Median age was 35 days. Preoperative TV insufficiency was absent or trivial in 59 patients (39%), mild in 72 patients (47%), moderate in 13 patients (8%), and severe in 9 patients (6%). The TV was quadricuspid in 36 patients (24 %), bicuspid in 10 patients (7%), and tricuspid in the remaining patients. At surgery, TV plasty (n = 6) or replacement (n = 3) was associated with truncus arteriosus repair. Truncal valve-aorta continuity was restored by patch interposition in 27 patients (17%), by conduit in 7 patients (5%), and directly in the remaining patients. Results: A 97-month mean follow-up was achieved in all survivors. The actuarial survival rates were 81.7% ± 3.1% and 79.1% ± 3.3% at 6 months and 18 years, respectively. Among 85 patients who underwent 113 reoperations, 19 underwent 24 TV reoperations: 5 isolated TV reinterventions and 19 associated with right ventricular-pulmonary artery conduit replacement. Freedom from TV reoperation was 96%, 82.3%, and 62.7% at 1, 10, and 18 years, respectively. Multivariate logistic regression showed that moderate or severe TV insufficiency at initial presentation was a risk factor for late TV reoperation but not for early mortality. Initial TV replacement was associated with lower survival. Conclusions: Initial TV insufficiency is associated with higher reoperation rate. This condition requires more refined techniques of TV plasty. The overall long-term freedom of TV reintervention rate remains within reasonable ranges. Truncal valve reintervention presents a low risk for mortality.