Abstract: Objective :To investigate the expression of the coxsackie and adenovirus receptor (CAR) in renal cell carcinoma and its relationship with the biological behaviors. Methods :The method of mmunohistochemistry SP was used to detect the expression of CAR in 48 cases with renal cell carcinoma tissue and 12 cases with paraneoplastic normal renal tissue (about 2 cm away from tumorous tissue). Results :The positive rate of CAR was 100% in the 12-case group and 35.4% in the 48-c asegroup (31 cases). The difference of CAR expression between the two groups was significant (P<0.05). The positive rate of CAR in I grade (22 cases), II grade (17 cases) and III grade (9 cases) was 54.5%, 23.5 % and 11.1 %,respectively, and there was a negative correlation between CAR expression andgrading (P<0.05). Meanwhile, the the positive rate in stage I with 19 cases, stage II with 13, stage III with 11 and stage IV with 5 was 57.9%,30.8 %,18.2% and 0.0%,respectively. So, there was a relationship between the CAR expression and the staging (P<0.05). Conclusions :The loss of CAR geneexpression occurs in most of the renal cell carcinoma. The change in the level of CAR expression correlates with the grading and staging of renal cell carcinoma and can be a sensitive predictor of differennation, and metastasis of renal carcinoma.