The relation of atrophic gastritis, other gastric lesions and lifestyle factors to stomach cancer risk was prospectively studied among 3,914 subjects who underwent gastroscopic examination and responded to a questionnaire survey at the Aichi Cancer Center Hospital. During 4.4 years of follow-up on average, 45 incident cases of stomach cancer were identified at least three months after the initial examination. If the baseline endoscopic findings indicated the presence of atrophic gastritis, the risk of developing stomach cancer was increased 5.73-fold, compared with no indication at the baseline. The risk further increased with advancing degree of atrophy and increasing extension of atrophy on the lesser curvature. These trends in the relative risks were statistically significant (P = 0.027 and P = 0.041, respectively). The risk of developing stomach cancer was statistically significantly increased among subjects with gastric polyps, but not among those with gastric ulcer. Stomach cancer cases tended to consume more cigarettes, alcohol, rice, pickles and salted fish gut/cod roe and less fruits and vegetables and to have more family histories of stomach cancer than noncases, although these differences were not statistically significant. The results of the present study provide additional evidence on the relation between atrophic gastritis and stomach cancer and suggest a need for intensive follow-up of patients with atrophic gastritis and gastric polyps.