Abstract: BACKGROUND ＆ AIM： To evaluate the effects of green tea (GT) on Microcystin-LR (MC-LR)-induced hepatocelluar apoptosis, Bcl-2 expression and micronucleus test so as to explore antagonistic mechanism of GT. MATERIALS AND METHODS： 50 male mice were randomly divided into five groups. Mice in GT pretreated groups were given green tea as free drink at doses of 2 g/(L·d) and 12 g/(L·d) prior to MC-LR intoxication, consecutively for 18 days. The toxin treatment mice in group MC-LR control received continual intraperitoneal injections of MC-LR at dose of 10 μg/(kg·d) for 13 days from day 6 till sacrifice. CP control group was treated with intraperitoneal cyclophosphamide twice at dose of 50 mg/(kg·d) 24 h interval on days 17 and 18. Mice were sacrificed and immediately subjected to autopsy. Hepatocellular apoptosis, Bcl-2 protein expression and micronucleus frequencies of bone marrow were evaluated immediately. RESULTS： (1) MC-LR induced obvious hepatocellular apoptosis. High dose of GT pretreatment significantly inhibited MC-LR-induced hepatocellular apoptosis(P<0.05).(2) There was no significant change of Bcl-2 protein expression in MC-LR control compared with control. As compared with only MC-LR, the expression of Bcl-2 protein was significantly increased in GT pretreatment groups(P<0.01).(3) No significant difference in micronucleus frequencies was found in either MC-LR control or GT pretreatment groups compared with control (P>0.05). CONCLUSION： GT could increase Bcl-2 protein expression and inhibit hepatocellular apoptosis，MC-LR and GT pretreatment did not cause damage to mice chromosome.

Key words: green tea, microcystin-LR, apoptosis, bcl-2, micronucleus