The pharmacokinetics of DWP302, a new combined ranitidine preparation in rats and dogs was studied using HPLC. DWP302 was composed of ranitidine, sucralfate and tripotassium dicitrato bismuthate. Especially, this study was focused on the possibilities that the concomitant administration of either sucralfate or TDB may affect the absorption of orally administered ranitidine. Ranitidine and DWP302 were orally administered to rats at a dose of ranitidine 10mg/kg. Several rats showed the biphasic peak of plasma concentration. AUC$_{S_{0-8}}$ of ranitidine and DWP302 group were found to be 1040$pm$109 and 945$pm$124 ng.hr/ml, respectively, and there was no significant difference between both AUCs. In a cross-over study for dogs, $C_{max}$, t$_{1/2}$ beta and total AUC of ranitidine group were found to be 625.8$pm$86.7 ng/ml, 2.80$pm$0.28 hr and 1688$pm$127 ng.hr/ml, and those of DWP302 group were 562.6$pm$120.9 ng/ml, 3.05$pm$0.30 hr and 1673$pm$123 ng.hr/ml, respectively. There was no significant difference between those parameters, but Tmax of DWP302 group (1.69$pm$0.31 hr) was significantly different from ranitidine group (1.13$pm$0.26 hr). The results suggest that either sucralfate or TDB may affect the lag-time or rate of absorption of ranitidine but not the extent of absorption.