BACKGROUND: Experimental and epidemiologic evidence suggests that folate may play a role in the development of some cancers. Case-control studies and one prospective cohort study on folate intake in relation to stomach cancer risk have yielded inconsistent results. METHODS: We prospectively investigated the relation between folate intake and the incidence of stomach cancer among 61,433 women in the Swedish Mammography Cohort. Participants completed a food frequency questionnaire at baseline (1987-1990) and again in 1997. During follow-up through December 2004, 156 incident stomach cancer cases were diagnosed. Cox proportional hazards models were used to calculate multivariate-adjusted hazard ratios. RESULTS: There was no association between dietary folate intake (i.e., folate from food sources) and the risk of stomach cancer. The multivariate hazard ratio for the highest compared with the lowest category of updated average dietary folate intake was 1.04 (95% confidence interval, 0.61-1.86; P(trend) = 0.91). The relation between dietary folate intake and stomach cancer did not vary significantly by intake of alcohol, methionine, or caffeine. CONCLUSION: Results from this prospective study do not support an association between dietary folate intake and risk of stomach cancer.