Congenital muscular torticollis is a distinct entity, in which the primary pathologic picture is limited to the sternocleidomastoid muscle. Associated deformities of the face, head and cervical spine are secondary in character, resulting from an abnormal position of the head both prior and subsequent to birth. The etiology of congenital muscular torticollis is not clear yet. There are various opinions about adequate age and methods for treatment. From January 1970 to December 1984, 53 cases of congenital muscular torticollis were treated surgically at the Department of Orthopedic Surgery, Severance Hospital. From January 1980 to December 1984, 10S cases of congenita muscular torticollis were treated conservatively at the same hospital. Totally, 161 cases were studied and analyzed retrospectively and the results are summerized as follows: 1. Among the 161 cases, thers were 88 males and 73 females. The lesion was on the left side in 89 cases. 2. There were 85 cases of normal spontaneous vaginal delivery and 58 cases of complicated labor including 34 cases of breech delivery. 3. There were 6 cases associated with other congenital anomalies; one of them was combined with congenital subluxation of the hip joint. 4. Results of conservative physiotherapy were good under 1 year of age and results of surgical correction were good under 6 years of age. 5. The failure of conservative physiotherapy did not influence the results of surgical correction performed later. 6. The results of reoperation, when the initial surgical correction failed, were not as good. 7. Facial asymmetry correction results were especially good under 6 years of age when much growth potential remained. 8. There were no differences in results according to the various kinds of cervical braces although the results were good when the cervical brace was worn over 3 months. 9. On pathologic examination, there was no hemorrhagic reaction. The muscle was atrophied and was replaced by fibrous bands. Therefore, congemtal muscular torticollis is thought to be caused by abnormal intrauterine position rather than by birth trauma, and it is expected to get a good result by treating congenital muscular torticollis as early as possible.