Abstract: OBJECTIVE To observe the effects of Linderae Radix on the immunological function of mice and experimental fatty liver of rats. METHODS ICR mice were orally administered with 4, 2 and 1 g·kg^-1 dosage of Linderae Radix respectively. The organ index of spleen and thymus, T lymphocyte transformation ability, the numbers of antibody producing cells were observed at the 30th day. SD rats modeled with taking high-fat diet were orally administered with 2, 1 and 0.5 g·kg^-1 dosage of Linderae Radix respectively for 21 d. Serum levels of TC, triglyceride(TG), low-density lipoprotein cholesterol(LDL-C), high-density lipoprotein cholesterol(HDL-C), alanine aminotransferase(ALT) and aspartate aminotransferase(AST) were detected at the 21st day. RESULTS Compared with the control group, 4, 2 g·kg^-1 Linderae Radix could raise the organ index of thymus, enhance the ability of T lymphocyte transformation and increase the number of antibody-producing cells. The 4, 1 g·kg^-1 dosage could raise the organ index of thymus. Compared with the model group, 2 g·kg^-1 of Linderae Radix could reduce the serum level of TC, LDL-C, AST, ALT of the model rats, 1 g·kg^-1 dosage could reduce the serum level of TC, AST of the model rats. CONCLUSION Linderae Radix can enhance the immunological function of mice and has hepatoprotective effect on experimental fatty liver of rats.