OBJECTIVE： To study the effects of artificial Isaria cicadae cystocarp on gentamicin-induced acute renal failure in mice， and to investigate potential mechanism preliminarily. METHODS： Totally 48 mice were randomly divided into blank group （normal saline）， model group （normal saline）， verapamil group （positive control， 21.43 mg/kg）， artificial I. cicadae cystocarp high-dose， moderate-dose and low-dose groups （5， 2.5， 1.25 g/kg）， with 8 mice in each group. Except for blank group， other groups were given gentamicin 200 mg/kg intraperitoneally to induce acute renal failure model； 2 h after intraperitoneal injection of gentamicin， each group was given relevant medicine intragastrically， once a day， for consecutive 7 d. 4 h after last administration， the contents of BUN， Scr and total protein in serum were determined， and renal indexes were calculated. The contents of MDA， SOD and activity of Na+-K+-ATP enzyme in renal tissue were determined； the changes of renal histopathological were observed by naked eye or microscope after HE staining. RESULTS： Compared with blank group， the serum contents of BUN and Scr， the content of MDA in renal tissue and renal indexes were increased significantly in model group （P＜0.01）； the serum content of total protein， the content of SOD and activity of Na+-K+-ATP enzyme in renal tissue were decreased significantly （P＜0.01）. The pathological changes of renal tissue were observed by naked eye， such as swelling， congestion. Pathological injury of renal tissue was founded under microscope， such as severe granularity and vacuolar changes in renal tubular epithelial cells， epithelial cell exfoliation. Compared with model group， serum contents of BUN and Scr， content of MDA and renal indexes of renal tissue were decreased significantly in each administration group （P＜0.01）； SOD content of renal tissue in artificial I. cicadae cystocarp high-dose and medium-dose groups， activity of Na+-K+-ATP enzyme in renal tissue in each administration group were increased significantly （P＜0.01）. The pathological injury of renal tissue in different administration groups were also improved to varying degrees， especially artificial I. cicadae cystocarp high-dose and medium-dose groups. CONCLUSIONS： The artificial I. cicadae cystocarp has a significant protective effect on the gentamicin-induced acute renal failure in mice， the mechanism of which may be related to the alleviation of renal damage and antioxidant function.