Objective This study explored the effects of Epimedium koreanum Nakai(EK)on liver function in normal,kidney yang deficiency(KYANGDS),and kidney yin deficiency(KYINDS)rats based on the theory of"You Gu Wu Yun."The study also investigated the connection between EK-induced liver injury and symptoms.Methods Seventy-two male SD rats were divided into normal,KYANGDS,and KYINDS groups using the random number table method.The KYANGDS model was established through intramuscular injection of 20 mg/kg of hydrocortisone,whereas the KYINDS model was established through daily gavage of 160 mg/kg of thyroid tablet suspension for 14 consecutive days.After successful modeling,the rats were divided into the normal,EK low-dose,EK high-dose,KYANGDS,KYANGDS+EK low-dose,KYANGDS+EK high-dose,KYINDS,KYINDS+EK low-dose,and KYINDS+EK high-dose groups using the random number table method.Animals in the drug groups were administered low(0.26 g/kg)and high(0.77 g/kg)EK extract doses through continuous gavage.The other groups received drinking water once a day for 28 consecutive days.Changes in body mass were monitored during the administration period,and serum alkaline phosphatase(ALP),alanine transaminase(ALT),aspartate transaminase(AST),direct bilirubin,indirect bilirubin(IBil),and total bilirubin(TBil)were measured at the end of administration using biochemical analyzers.The liver weight,visceral body ratio,and visceral brain ratio were measured.Hematoxylin and eosin staining were performed to observe the pathological changes in the liver.Results Compared with the normal group,the EK high-dose group showed a decrease in body weight on the 21st day during the drug administration period and an increase in IBil(P<0.05);the KYANGDS group had lower body weight at each measurement time point from the third to the 28th day,higher ALP,and lower liver weight(P<0.05).Compared with the KYANGDS group,the KYANGDS+EK high-dose group had decreased ALP levels(P<0.05).The pathological damage of liver tissue in each KYANGDS administration group improved,the presence of fat vacuoles were reduced,and pathological scores show a decreasing trend.Compared with the KYINDS group,KYINDS+EK high-dose group exhibited a higher IBil level and a lower visceral brain ratio(P<0.05).Conclusion EK has a small effect on the liver function of rats with KYANGDS within the dose range;however,it has a specific hepatogenic impact on normal and KYINDS rats,and EK-induced liver injury and the symptoms may be associated with each other.