The effect of methanol extract of root bark of Azadirachta indica was investigated in mice to evaluate the antiulcerogenic activity. Total phenolics were also determined. The root barks of have been extracted by Azadirachta indica successive solvent extraction method. Extracts were subjected to phytochemical analysis and total phenolics were also determined by the modified Folin-Ciocalteu method. The parameters taken to assess anti-ulcer activity were volume of gastric secretion, pH, free acidity, total acidity, and ulcer index and % ulcer protection. The results indicated that the methanol extract significantly (p< 0.001) decreases volume of gastric acid secretion, pH, free acidity, total acidity and ulcer index and shows significant ulcer protection compared to standard control. Root bark extracts found to possess significant amount of phenolics and other biologically active constituents based on phytochemical evaluation and shows significant antiulcerogenic activity. Keywords : Azadirachta indica, Root bark,