From October 1962 to Agusut 1967, thirty two cases of incompetent internal os of the cervix were treated at the Department of the Obstetrics and Gynecology, College of Medicine, Seoul National University. Shirodkar operation was performed in 27 cases during the second trimester of pregnancy and resul- ted in viable term delivery in 21 cases, three premature delivery, with a success rate of 77.8% & 1 1.0% respectively. McDonald Technique was carried out in four cases and resulted in three te- rm delivery and one premature delivery, with a success rate of 75%. In one case Wurm procedure was carried out and resulted in dremature deivery. We reviewed these cases, with a brief review of the literature.