The objective of this study was to compare early postoperative results in primary vs 2-stage repair of tetralogy of Fallot in patients operated on after 5 years of age. Eighty-four patients with tetralogy of Fallot were studied, who were more than 5 years of age and who were repaired in one center by one surgeon. Hospital death and ratio of right-to-left ventricle pressure after correction were compared between the primary and the 2-stage groups as early outcome indices. Overall hospital mortality was 11.9% (10/88). There were 9 (18.4%) hospital deaths in the primary and 1 (2.9%) in the 2-stage group. Mortality was significantly higher in the primary group (p = 0.04 using the 2-tailed Fisher's exact test; relative risk = 6.43; 95% CI = 0.85-48.46). The mean +/- standard deviation (SD) for RV/LV ratio was 0.51 +/- 0.13. It was 0.61 +/- 0.11 in patients who died and 0.49 +/- 0.12 in patients who lived (p = 0.01 using the 2-tailed t-test). RV/LV ratio was not significantly different between either group. In the 2-stage group, there was a small inverse correlation between the time interval and the RV/LV ratio (correlation coefficient = -0.235). The TAP group had a statistically significant lower time interval between shunt and total correction than the RVOT-P group (p = 0.02 using 2-tailed t-test). Older patients generally do better on 2-stage repair, because of their age. A long period of low pulmonary blood flow has induced unbalanced ventricles and exaggerated RVOTO for these patients because of muscle hypertrophy. In such patients, shunting will prepare the left ventricle for accepting the extra blood volume that will reach the left ventricle after total correction.