In order to identify factors that may explain the great variation in mortality from esophageal cancer in Shanxi Province, China, an ecological study was carried out in 21 communes in that province. Mortality data were obtained from the registration records of the population of 148,928 during 1983 to 1988, which provided 744,640 person-years of observation. The data regarding average consumption of each kind of grain, potatoes and sweet potatoes were from food allocation records. The data regarding consumption of meat, eggs, fruit, vegetables and the data regarding alcohol drinking were from interviews. The concentrations of nitrite and of nitrate in pickled vegetables and in drinking water were measured. A significant positive relation was found between mortality rate and the consumption of dietary corn and wheat flour. Also, a significant inverse relation was found between the mortality rate and the dietary sorghum and millet level. The age- and sex-adjusted mortality-rate ratio of esophageal cancer for residents in the third and highest quartiles of corn- and wheat-flour consumption are 1.4 (95% CI: 1.1-2.0) and 3.2 (2.5-4.2), respectively, compared with those in the lowest quartile. Other factors studied did not contribute to the great variation in esophageal cancer mortality in the areas studied.