Objective:To detect the hepatic toxicity after giving large dose of Radix et Rhizoma Sophorae Tonkinensis（RRST） to rats for a long time.Method: The rats were divided into 3 groups（control group

12 g.kg-1 drug group

20 g.kg-1 drug group） and given the drug for 26 days.During the days

the rats’behave and weights were observed.After giving the drug for the last time

the rats were anaesthetized by 25% Urethane and the rats’blood was extracted from aorta abdominalis

then liver function was detected by using the blood serum.The rats’livers were taken and weighed

after that

the viscera index was calculated.According to the demand of electron microscope

hepatic tissues were fixed and ultrastructures were detected.Biochemical indicators such as ALT

AST

ALP

TBiL

TP

GLO and ALB were detected by using automatic analyzer.Result: After giving RRST for 10 days

the activity of the rats in drug group decreased

what’s more

the rats had general fatigue and the amount their excrement and urine increased.After giving drug for 26 days

compared with normal group

the ALT and viscera index increased in drug group（P < 0.01 or P < 0.05）

the TP

ALB decreased in drug group（P < 0.01 or P < 0.05）;Through the electron microscope

the results showed that in RRST group

the shape of nucleus changed

nucleus had the tendency of swelling

nuclear membranes shrunk

bile capillaries enlarged and smooth surfaced endoplasmic reticulum enlarged slightly.Conclusion: RRST can cause hepatic toxicity in rats by intragastric administration and the toxicity will increase if the dose of drug is added.