In order to compare the efficacies of some surgical procedures for correction of congenital muscular tortiollis, we evaluate 36 patients who had been treated either by unipolar release (19 patients) or bipolar release (17 patients) of the sternocleidomastoid (SCM) muscle at Seoul National University Children Hospital from August 1985 to June 1993. The average follow up period was 4.1 years (range, 1 year to 7 years and 8 months). The average ages at the time of operation was 3.4 years (range, 11 months to 7 years and 1 month) in the unipolar group and 9.7 years(range, 4 years and 5 months to 16 years and 11 months) in the bipolar group. Postoperatively, flexion and extension range of motion of the neck was not limited of limited less than 10 degrees, if present, in all cases. In rotation motion, 89.4% of the unipolar group and 94.1% of the bipolar group showed no limitation or limitation of less than 10 degrees when compared to the normal side postoperatively. In lateral bending, however, 21.1% of the unipolar group and 21.5% of the bipolar group showed limitation of more than 10 degrees when compared to the normal side postoperatively. Facial asymmetry, which was present in 89.4% of the unipolar group and all cases of bipolar group preoperatively, disappeared in 73.7% of the unipolar group and 23.5% of the bipolar group and improved in 94.1% of the unipolar group and 64.7% of the bipolar group. The over-all functional and cosmetic results were assessed according to the modified Ling's criteria. In function results, 14 patients(73.3%) had excellent or good results in unipolar group and 12 patients(70.6%) in bipolar group. In cosmetic results, 15 patients(78.9%) had excellent or good results in unipolar group and 11 patients(64.7%) in bipolar group. Recurrence rate was higher in the unipolar group (15.8%) than in the bipolar group (5.8%). In conclusion, limitation of lateral bending was more resistant to the treatment than the limitation of rotation. Bipolar release of SCM muscle would be recommendable even in young children in terms of recurecce.