Abstract： Objective To observe the levels of Livin and Caspase-3 in renal tissue of rats following acute paraquat (PQ) poisoning and the intervention effects of ulinastatin (UTI) . Methods Fifty-four Sprague-Dawley (SD) rats were randomly divided into three experimental groups: control group (group A),PQ poisoning group (group B) and UTI group (group C) (n = 18 in each group) . Rats in group B and group C were administered intragastrically with 80 mg/kg PQ, and rats in group C were treated with 100,000U/kg ulinastatin injected intra-psritoneally once a day; and rats in group A were administered intragastrically with the same volume of saline instead of PQ. At 24, 48, 72 hours after poisoning, the levels of Livin in renal tissue were detected by Westen blotting and the levels of Caspase-3 were detected by immunohistochemistry 24, 48, and 72 hours after poisoning, and the histopathological changes of renal tissue were observed at the same time. Results In the group A, the structure of renal tissue was distinct. In the group B, the distinctness of the structure of renal tissue declined significantly, and swelling, edema and vacuolar degeneration were observed 24 h after poisoning, and pathological changes became more and more obvious keeping pace with time elapsing, and sometimes karyopyknosis appeared and celluar structures disappeared with involvement of renal glomerulus and medulla. These pathological changes were significantly lessened in rats of group C. In the group A, there was little Caspase-3 in renal tissue of rats. Twenty-four hours after poisoning, the caspase-3 in renal tissue of rats of group B was found on the membrane and in the kytoplasm of renal tubular epithelial cells of cortical part. Compared with group B, the level of Caspase-3 in renal tissue of rats of group C decreased significantly to lower level (P ＜0. 01 ) . Compared with group A,the levels of Livin in renal tissue in rats of group B and group C increased significantly at all different intervals (P ＜0. 01 ), and as group B was compared with group C, the difference was statistically significant (P ＜0. 01 ) . Conclusions The main pathologyical changes of renal injury induced by PQ are epithelial swelling, vacuole degenerateion and necrosis. Caspase-3 is involved in the process of renal injury. UTI has a protective effect on the renal tissue of rats following paraquat poisoning through up-regulating the level of Livin and down-regulating the level of Caspase-3, however, the regulation mechanism as well as the pathway is still needed to further study.