Experimental gastritis was produced in rats by administration of sodium taurocholate (5 mM) for 3 months. The gastritis was associated with mucosal surface injury (erosion), inflammatory cell infiltration and proliferation of interstitial fibrosis in the gastric mucosa. The number of parietal cells per unit area and the mucosal thickness, however, were not different from those in the normal mucosa, indicating that this kind of gastritis was not atrophic but erosive gastritis. The model of erosive gastritis is most useful in studies on gastroprotection and various drugs.