Abstract: OBJECTIVE To study the effects of roxithromycin, levofloxacin and fluconazole on the metabolism of simvastatin in human liver microsome respectively. METHODS Simvastatin was incubated with roxithromycin, levofloxacin and fluconazole in human liver microsome. The residual concentration of simvastatin in human liver microsome incubates was determined by UPLC-MS/MS. RESULTS The roxithromycin and levofloxacin had no significant influence on the metabolism of simvastatin. The IC₅₀ of fluconazole for the metabolism of simvastatin was 36.6 μmol·L^-1 and the inhibit intension was dose dependent. CONCLUTION The fluconazole significantly inhibits the metabolism of simvastatin. The roxithromycin and levofloxacin have no significant drug interactions on the metabolism of simvastatin.