In this study, we evaluated the management of incidental adnexal masses observed at the time of cesarean section in our clinic during January 1992 to January 2005. The number of total live births was 35,153 and 8330 of them were by cesarean section (23.69%). There were 68 cases of incidental adnexal masses greater than 5 cm (68/8330, 0.8%). All of the masses were removed at cesarean section. The pathologic diagnosis of the masses were as follows: benign—benign cystic teratoma 20 (29.4%), simple serous cyst 8 (11.8%), simple mucinous 9 (13.2%), endometrioma 3 (4.4%), cystadenoma 14 (20.6%), and paraovarian–paratubal cyst 13 (19.1%) and malignant—struma ovarii 1 (1.5%). Cystectomy procedure during cesarean section did not alter the morbidity of the operation. So, we recommend resection of such incidental adnexal masses at cesarean section to avoid possible surgical procedures in future for the patient, although there is controversial data in literature.