Abstract: OBJECTIVE To discuss the reverse effect of gastric atrophy and the influences to PCNA and Bcl-2 protein, PCNA mRNA, Bcl-2 mRNA, TFF3 mRNA, TNF-α mRNA of American Ginseng alcohol extracts for the treatment of the model rats with chronic atrophic gastritis(CAG) induced by N-methyl-N'-nitro-N-nitrosoguanidine(MNNG). METHODS Wistar rats were free to drink MNNG solution with a concentration of 167 μg·mL^-1, and they were made models for 12 weeks. After making the model successfully, divided the rats into model group, normal group and American Ginseng alcohol extracts group. After giving drugs intervention separately, observed the weight of rats, gastric tissue histopathology, gastrin(GAS), the expression of PCNA and Bcl-2 protein and mRNA, TFF3, TNF-α mRNA in gastric tissue. RESULTS In the eighth therapeutic week, the weight of rats in the American Ginseng alcohol extracts group were significantly higher than the model group(P<0.05). The glandular atrophy, atypical hyperplasia and intestinal metaplasia were significantly relieved in the American Ginseng alcohol extracts group(P<0.01). There was no significant difference of gastric mucosa inflammation level GAS between the American Ginseng alcohol extracts group and the model group. There were significant reduce of content of the PCNA protein and Bcl-2 protein in the American Ginseng alcohol extracts group(P<0.01). In the American Ginseng alcohol extracts group, there was a decline of PCNA mRNA, TFF3 mRNA and TNF-α mRNA but had not significant, Bcl-2 mRNA was significantly increased compared with model group(P<0.01). CONCLUSION American Ginseng alcohol extracts have a good therapeutic effect on the CAG model rats in reducing weight loss and reducing gastric atrophy and intestinal metaplasia, one of the mechanism may be down regulating the high expression of PCNA and Bcl-2 in gastric mucosa, and to improve and even reverse the pathological state of CAG.