Abstract: Objective To investigate the expression of osteopontin(OPN) and its clinicopathological significance in ovarian tumors. Methods The expression of OPN was detected by immunohistochemistry method. In 54 cases of ovarian malignant tumor tissues, 20 cases of ovarian borderline tumor tissues, 20 cases of ovarian benign tumor tissues and 10 cases of normal ovarian tissues. Results The positive expression rate of OPN was 77.80% in ovarian malignant tumors, much higher than ovarian borderline tumors（35％）and ovarian benign tumors（15%）,（P<0.01）. There was no OPN expression in normal ovarian tissues. The positive rate of OPN expression was dramatically higher in stage Ⅲ～Ⅳ tumor tissues than that in stageⅠ～Ⅱ ones（P＝0.029）.The expression of OPN was also significantly higher in the patients with out metastasis than that in the patients with no metastasis (P＝0.019). The overall survival of the patients with OPN positive expression was significantly shorter than that of the negative ones（P＝0.038）. OPN expression was independent factor to decrease overall survival. Conclusion Overexpression of OPN may play an important role in the malignant transformation,development,invasion and metastasis of ovarian cancer. It has a potential clinical significance as a prognostic marker in ovarian cancer patients.