Abstract: Objective The purpose of this study was conducted to investigate the expression of Signal transducer and activator of transcription 3(STAT3) and target gene products including Cyclin D1 and Caspase-3 in human ovarian carcinoma tissues,and to explore the mechanisms in tumorigenesis of ovarian carcinoma. Methods Primary ovarian cancers and normal ovarian tissue were obtained from 40 patients undergoing ovarian cancer resection.Western blot analysis was used to measure the expression of STAT3,p-STAT3,Cyclin D1, and Caspase-3 in cancerous tissues, normal ovarian tissues. Results 　p-STAT3, Cyclin D1, and Caspase-3 protein levels were increased in ovarian cancer compared with adjacent normal tissue ( P = 0. 028, 0. 035, 0. 047) . Overexpression of p-STAT3 and Cyclin D1 were correlated with FIGO stage in ovarian cancer ( P = 0. 026, 0. 041) . It was found that Cyclin D1 was in a positive line-arcorrelation fashion with p-STAT3 in tumor ( r = 0. 412, P < 0. 05) . Conclusion 　These findings provide evidence that STAT3 signaling pathway may play an important role in the tumorigenesis of ovarian carcinoma, and detecting the expression of STAT3 and it s target gene product s may predict the malignant potential of ovarian carcinoma.