Abstract: OBJECTIVE To investigate the inhibition of genkwanin and apigenin on UGTs and UGT1A1 activities of different liver microsomes. METHODS In the present study, in vitro liver microsornal incubation model was used. 4-nitrophenol (4-NP) and bilirubin were elected as substrates to determine activities of UGTs and UGT1A1 by UV and UPLC-MS/MS, respectively. RESULTS Genkwanin and apigenin significantly inhibited UGTs activity in rats, mice and human liver microsome. In rats liver microsome temperature hatch system, the inhibition strength suitable genkwanin was higher than apigenin. In mice and human liver microsome temperature hatch system, the inhibition strength suitable apigenin was higher than genkwanin. UGT1A1 activity was inhibited by genkwanin and apigenin with IC₅₀ about 23.21, 12.40 μmol·L^-1 in human liver microsome, respectively. The inhibition types were competitive inhibition. Inhibition of apigenin was better than genkwanin. CONCLUSION The results indicate that genkwanin and apigenin show different level of inhibition effects. This result may be caused drug interactions based on UGT1A1 enzyme.