Objective:To investigate the expression of c-Fos and c-Jun in AGS cells by stimulation of H. pylori. Methods:The gastric cancer AGS cells were treated with the different types of H. pylori(isolated from gastritis, ulcer or gastric cancer) for one hour, respectively. The lysate of the cells were collected to detect the expression of the two genes by Western blot. Results:The expression of c-Fos protein in the cells stimulated by ulcer type and that of c-Jun by gastritis type increased obviously. Furthermore, the expression of proteins of c-Fos and c-Jun by the stimulation of gastritis and ulcer types mixed was more increased than that of single type of H. pylori and so was the expressions of c-Fos and c-Jun by stimulation of the mixture of the three types. However, there were unremarkable expression changes of the two proteins in the cells treated only with the type of gastric cancer. Conclusion:There was difference in the proto-oncogene c-fos and c-jun expression in AGS cells stimulated with different types of H. pylori. The expression of the two genes was more sensitive in the AGS cells treated with multi types of H. pylori. It indicated that the cancer occurrence was promotered by mixed infection of multi types of H. pylori.