Abstract: Rhizophora apiculata, a mangrove specie is used in traditional medicine against several human diseases including tumor. To validate the ethnopharmacological claims against cancer, we examined the effects of Rhizophora apiculata leaf oil on the anti gastric cancer activities of Benzo(a)pyrene (BaP) induced gastric cancer in albino mice. The animals were divided into five groups. Group I were given BaP (40 mg kg-1 b.wt.) with 100 μL sesame oil by oral gavage twice a week for 4 consecutive weeks. Group II were given 100 μL sesame oil (SMO) treated (Vehicle treated control) a week for 4 consecutive weeks. Group III mice (BaP) (40 mg kg-1 b.wt.)+R. apiculata (50 μL) for 14 weeks. Group IV only R. apiculata (50 μL kg-1 b.wt.) dialy for two weeks. Goup V as the control non treated. At end of 14 weeks, all the animal were killed. Tumor incidence was observed to be 100% in mice that received only BaP. However, treatment with R. apiculata oil reduced the tumor incidence as observed in mice of BaP+R. apiculata oil group when compared to that of BaP group. Similarly, the tumor burden and body weight were seen to decrease by 137.21, respectively in mice of BaP+R. apiculata oil group when compared to those of BaP group. Diminished lipid peroxidation in the stomach tumor tissue was associated with enhanced antioxidant levels. In contrast to tumor tissue, enhanced lipid peroxidation with compromised antioxidant defences was found in the liver and erythrocytes of tumor bearing animals. Administration of R. apiculata oil significantly reduced the incidence of stomach tumors, modulated lipid peroxidation and enhanced antioxidant status in the stomach, liver and blood. From the results of our study, we suggest that R. apiculata oil may exert its chemopreventive effects by modulating lipid peroxidation and enhancing the antioxidant status in the stomach, liver and erythrocytes.