The effects of Monosodium glutamate (MSG) on gastric acid secretion, gastric mucus secretion and gastric ulceration were studied in adult albino rats of Wistar strain. The treated animals were given subcutaneous injection of 0.6 mg g-1 MSG for 30 days. Mean basal gastric acid secretion in control versus MSG treated rats were not significantly different; 1.45±0.06 vs 1.40±0.02 (p>0.05). However, MSG significantly increased histamine-induced gastric acid secretion with time (p<0.05). Mean ulcer scores and gastric mucus secretion were significantly higher in MSG-treated animals than in the control (p<0.05). The values are 7.63±1.02/15.75±1.43 and 5.95±0.51/12.75±0.78, respectively. MSG was found to produce nonuniform histopathologic changes in gastric mucosa, which were characterized by edematous lamina propria containing increased numbers of inflammatory cells, vascular congestion and disruption with lifting rupture.