Abstract：Objective To explore the clinical significance of carbohydrate antigen 199 (CA199) in diagnisis of ovarian teratoma. Methods The retrospective analysis of the tumor marker CA199 test results of 138 patients in ovarian teratoma who were treated by the gynecology in our hospital was carried out. Results The positive rate of tumor marker CA199 in ovarian teratoma was high. The positive rate was related with the age of the patient, the size and the region (unilateral or bilateral) of the tumor. Conclusion The detection of CA199 has certain clinical significance in diagnosis and differential diagnosis of ovarian teratoma. The detection of CA199 and combined with image data could be helpful to guide the clinical diagnosis and the treatment of ovarian teratoma.