Objective:To investigate the expression of glypican-3 (GPC3)protein and mRNA in ovarian clear cell adenocarcinoma and its correlation with clinical pathologic parameters. Methods:The expression of GPC3 protein was detected by immunohistochemistry in 83 cases of ovarian cancer including 45 clear cell adenocarcinoma,20 serous cystadenocarcinoma,18 mucinous cystadenocarcinoma,20 cases of serous cystadenoma and 20 cases of normal ovary. The expression of GPC3 mRNA was detected by real-time fluorescent quantitative polymerase chain reaction (RT-PCR) in 20 clear cell adenocarcinoma,10 serous cystadenocarcinoma,8 mucinous cystadenocarcinoma, 5 serous cystadenoma and 5 normal ovary tissues. The correlation between GPC3 expression and relative clinical pathologic parameters was analyzed. Results:①In ovarian clear cell adenocarcinoma, the positive rate of GPC3 protein and the mRNA expression (82.2%;1.326 1 ± 0.493 6) were significantly higher than those in ovarian serous cystadenocarcinoma (20%;0.426 5 ± 0.029 4),mucinous cystadenocarcinoma (5%; 0.265 2 ± 0.103 9),serous cystadenoma (0; 0.141 3 ± 0.011 3) and normal ovarian tissue (0; 0.291 4 ± 0.048 1)(P < 0.01); ②Both the expression of GPC3 protein and the mRNA were relevant to the clinical stage of ovarian clear cell adenocarcinoma. GPC3 expression in stage Ⅲ or Ⅳ (100%;1.808 1 ± 0.265 7) was significantly higher than that in stage Ⅰ or Ⅱ (71.4%;1.045 8 ± 0.403 6) (P <0.01) ;③Both the expression of GPC3 protein and mRNA were relevant to the status of cisplatin resistance. GPC3 expression in cisplatin-resistant patients (100%;1.808 1 ± 0.265 7) was higher than that in cisplatin-sensitive patients (70.3%;0.991 8 ± 0.330 3) (P < 0.05);④GPC3 protein expression was associated with survival of clear cell adenocarcinoma,which was higher in patients with poor prognosis (P < 0.05). Kaplan-Meier analysis showed that GPC3 protein expression was a prognostic factor (P=0.048);⑤GPC3 protein expression in ovarian clear cell adenocarcinoma had no relavance with the lymph node metastasis or distant metastasis (P > 0.05). Conclusion:GPC3 has an important significance in the differential diagnosis. There was a significant relationship between GPC3 expression and clinical stage and cisplatin resistance in ovarian clear cell adenocarcinoma. GPC3 may play an important role in the development of ovarian clear cell adenocarcinoma and could be used as a helpful prognostic marker and potential target .