A case-control study focusing on the role of single food items was undertaken in the Heilongjiang area, 241 patients with histologically verified stomach cancer and an equal number of controls (with non-neoplastic diseases) matched by age, sex and area of residence being interviewed during a 2-year period. Questions asked covered economic status, occupation, histories of smoking and drinking, diet and dietary habits and disease history. Data concerning the average frequency and quantity of consumption of single food items were obtained by the same interviewer. An inverse association between the consumption of vegetables and stomach cancer was observed whereas high intake of potatoes and of salted and fermented soya paste appeared to be high-risk factors. Specifically, Chinese cabbage plays an important role in reducing the risk of developing stomach cancer.