Objective:To test thein vitro protective role of aqueous extract ofOcimum gratissimumLinn. (O. gratissimum) and ascorbic acid against nicotine-induced murine peritoneal macrophage. Methods: Peritoneal macrophages from mice were treated with nicotine (10mM), nicotine (10 mM) with aqueous extract ofO. gratissimum (1 to25 μg/mL), and nicotine (10 mM) with ascorbic acid (0.01 mM) for12h in cell culture media, while the control group was treated with culture media. Levels of free radical generation, lipid peroxidation, protein carbonyls, oxidized glutathione levels andDNA damage were observed and compared.Results:Phytochemical analysis of aqueous extract has shown high amount of phenolics and flavonoids compound present in it. The significantly increased free radical generation, lipid peroxidation, protein carbonyls, oxidized glutathione levels andDNA damage were observed in nicotine-treated group as compared to the control group; those were significantly reduced in aqueous extract ofO. gratissimum and ascorbic acid supplemented groups. Moreover, significantly reduced antioxidant status in nicotine exposed murine peritoneal macrophage was effectively ameliorated by these two products. Among the different concentration of aqueous extract ofO. gratissimum, the maximum protective effect was observed at 10 μg/mL which does not produce any significant change in the normal cell.Conclusions:These findings suggest the potential use and beneficial role ofO. gratissimum as a modulator of nicotine-induced cellular damage in murine peritoneal macrophage.