OBJECTIVE To explore the effect of single dose and multiple doses of silibinin on the in vivo pharmacokinetics of nevirapine in rats. METHODS Thirty male SD rats were randomly divided into blank control group, multiple administration of low-dose group(30 mg·kg−1) , multiple administration of high-dose group(100 mg·kg−1), single administration low-dose group(30 mg·kg−1) , and single administration high-dose group(100 mg·kg−1). Blood samples were collected to determine the concentration of nevirapine and its metabolites in rat plasma after an oral administration of 10 mg·kg−1 nevirapine. The kinetic parameters of nevirapine and its metabolites in each group were calculated by DAS and analyzed statistically. RESULTS Compared with the blank control group, multiple doses of 100 mg·kg−1·d−1 silibinin significantly increased the AUC of nevirapine by 61.78%, Cmax by 124.62% and decreased the clearance rate to 64.11%; multiple doses of 30 mg·kg−1·d−1 silibinin significantly increased the Cmax of nevirapine by 84.85%; a single dose of 100 mg·kg−1 or 30 mg·kg−1 silibinin significantly increased the Cmax of nevirapine by 65.19% and 32.12%, respectively. The metabolic ratio of 12-hydroxy-nervirapine was decreased by 31.5% by multiple doses of 100 mg·kg−1·d−1 silibinin where the pharmacokinetic parameters of 4-carboxyl-nervirapine remained unchanged. CONCLUSION Silibinin significantly affects the pharmacokinetics of nevirapine in rats. The drug-drug interaction should be considered when nevirapine and silibinin are concomitant.