To determine correlates of the geographic variation in colon cancer mortality within China, dietary variables, biochemical markers, and other factors from an ecological survey in 49 Chinese rural counties were examined. High consumption of animal foods, salt-preserved vegetables, and beer was associated with increased mortality of colon cancer, whereas the rates were significantly inversely related with intake of green vegetables. Serum levels of total cholesterol, urea nitrogen, and lipid peroxide were positively correlated with colon cancer mortality, after adjustment for each other and for other blood nutrients. No appreciable associations, however, were found between colon cancer and serum levels of beta-carotene, alpha-tocopherol, vitamin C, and selenium. In addition, prevalence of schistosomiasis was significantly correlated with increased colon cancer mortality. This ecological study indicates that observations from earlier analytic investigations in Western societies may apply to a Chinese rural population and suggests that schistosomiasis and dietary factors may contribute to the remarkable geographic variation of colon cancer in China.