STUDY DESIGN A single-center, prospective study. OBJECTIVE To investigate the effect of rib anomaly on surgical curve correction outcome in congenital scoliosis. SUMMARY OF BACKGROUND DATA The presence of rib anomalies may complicate surgical correction of congenital scoliosis. The outcome of surgical correction, however, has not been documented in scoliotic patients with and without rib deformity. METHODS Percent Cobb angle decrease (CAD) after operation was calculated in 94 patients with congenital scoliosis. Posterior segmental pedicle screw instrumentation (posterior approach) with or without previous anterior spinal release and fusion (anterior approach) was the method of correction. The impact of vertebral anomaly and rib deformity on CAD was examined. RESULTS Although the type of vertebral anomaly had no significant effect on the mean CAD, it was significantly lower in 56 patients with rib deformity compared with that in the remaining patients without rib deformity (35.14%±15.83% vs. 51.54%±17.82%, P