Green tea catechins (GTCs) have been implicated in various physiological effects, including anti-carcinogenic activities. In the present study, we evaluated the effects of GTCs specifically on the development of gastritis and pre-malignant lesions in insulin-gastrin mice. Nine-week-old male INS-GAS mice (n=38) were supplemented with GTCs for 4 and 28 weeks, and their body weights, serum gastrin levels, histopathology and pro-inflammatory cytokine levels in gastric tissue and mucosal cell proliferation were monitored. Body weights of the GTC-treated mice were significantly lower than those of the untreated controls (P≤0.05). Serum gastrin levels were suppressed at the age of 37-weeks (P≤0.05). The histopathological scores indicated that the extent of dysplasia was significantly diminished (P≤0.05), although GTC supplementation did not affect the inflammation scores. The messenger RNA levels of interferon (IFN)-γ were significantly reduced at the age of 13 weeks (P≤0.05), although the changes did not reach statistical significance at the age of 37 weeks (P=0.056). The labeling index of Ki-67 immunohistochemistry was significantly decreased (P≤0.05). These results demonstrated that GTCs may play a protective role in the development of gastritis and pre-malignant lesions via an IFN-γ, gastrin, and mucosal cell proliferation-dependent mechanism in this rodent model and potentially in humans.