Abstract: Objective To study the expression of cyclooxygenase-2（COX-2） in renal clear cell carcinoma tissues and its relation with the clinical tumor stage.Methods Expression of COX-2 in renal tissue samples from 48 cases of cell carcinoma and in normal renal tissue samples from 28 healthy controls was detected by immunohistochemistry.Of the 48 cases of renal clear cell carcinoma,8,18,10 and 12 were staged as T1a,T1b,T2 and T3-T4,respectively.Results The positive expression rate of COX-2 in renal clear cell carcinoma tissue samples from 48 cases of cell carcinoma was 75%,which was located in cytoplasm and increased with the clinical tumor stage（r=0.731,P＜0.01）.COX-2 was negatively expressed in normal renal tissue samples from 28 healthy controls.Conclusion The expression of COX-2 is increased in renal cell carcinoma and is closely related with the clinical tumor stage,indicating that COX-2 can be used as a predictive factor for the development and progression of renal cell carcinoma,thus providing a theoretical basis for its application in treatment of renal carcinoma.