Abstract: The purpose of this study was to investigate the pharmacokinetic interaction between sunitinib and ramipril in rats. Eighteen male SD rats were divided into three groups, with each group being assigned to orally receive sunitinib, ramipril, sunitinib and ramipril, respectively, for ten days. Blood samples were collected at different times after first-day and tenth-day administration. The concentrations of ramiprilat and sunitinib in rat plasma were determined by LC/MS/MS and the pharmacokinetic parameters were calculated and statistically analyzed. Compared with the administration of ramipril alone, after a single-dose combined administration, t_max of ramiprilat decreased significantly and t_1/2 prolonged, while AUC_0-∞ remained unchanged. These results indicated that the absorption rate of ramiprilat increased and the elimination rate decreased, but total absorption degree was not changed. After multiple-dose administrations, CL of ramiprilat decreased and AUC_0-∞ increased obviously. It suggested that accumulation of ramiprilat occurred in body and the drug elimination became slower. No obvious difference of sunitinib pharmacokinetic behavior was found when it was given in combination with ramipril after a single-dose administration or multiple-dose administration. Sunitinib decreased the elimination of ramiprilat after co-administration in company with drug accumulation in body after multiple-dose co-administration. The study showed that there were pharmacokinetic interactions between sunitinib and ramipril in SD rats.