OBJECTIVE To investigate the risk factors of Helicobacter Pylori (Hp) infection. METHODS All cases and controls came from 561 cases of out-patients with stomach diseases seeking gastroscopy in the Zhejiang Province First Hospital between April and July in 2000. The tissue samples of patients were stained for Hp by the improved Warthin-Starry technique and by methylene blue stain for routine histopathology. We classified patients as cases or controls based on the detection of Hp or not. Before gastroscopy, a questionnaire on lifestyle and health condition of was administered to patients by the interviewers. RESULTS The overall prevalence of Hp infection was 50.21% and the risk factors of Hp infection were significantly different between males and females. As for males, the duration of daily heavy physical activities, numbers of siblings in the household, family history of oliver disease, preference of spicy food and smoking were the risk factors for Hp infection. However, preference of beans and bean products, drinking well water, drinking tea, eating regularly and good education appears to decrease the prevalence of infection. As for females, consumption of caffeine contained beverages seemed to increase risk for infection. By analyzing with unconditional Logistic Regression Model in male and female groups combined, it brought to light that intake of egg and peppery food were the risk factors of infection, and intake of beans and drinking tea were the protective factors. CONCLUSION Consumption of beans and drinking tea must be advocated and the consumption of spicy food should be discouraged.