Objective:To compare the morphologic and functional changes in kidney after cryoablation(CA)or radiofrequency ablation(RFA)for liver tissue in rats. Methods:In this study,ninety-four Sprague-Dawley rats were randomly divided into 2 groups. Group A(n=52)was treated with cryoablation by liquid nitrogen,which was performed in 15-20 s. Group B(n=42)was treated with RFA by using a cooled-tip technique. The energy output was 15 W for(60-90) s. All rats were sacrificed at prescheduled time,serum and tissue samples from the kidney were collected for subsequent analysis. Serum urea nitrogen(BUN),creatinine(Cr)in blood,and urine erytrocytes were measured prior to and 1,3,7,14 days after surgery. Histologic studies of kidney tissue were compared between two kinds of treatment groups. Results:At 1 day after ablation,serum concentration of BUN(P < 0.01),Cr(P < 0.01),and urine RBC(P < 0.05)in both groups increased evidently,which changed significantly in group A group B. In the early stage,many red-orange(hemoglobin-like)crystals appeared in the renal tubule lumen,and lymphocytes infiltration were found in group A. But these significant changes were not present in renal sections from the rats in group B. Conclusion:Hepatic tissue cryoablation results in severe renal dysfunction,but an approximate volume of liver parenchyma underwent RFA impacts lightly,which could be a safe therapy for liver tumor.