Objective To study the risk behaviors on diarrhea among the adults of Beijing.Methods 13287 adults aged over 18 years in Dongcheng,Xicheng,Haidian,Changping,Huairou and Tongzhou districts in Beijing were selected with a multi-stage stratified sampling method.Information on the demographic characteristics,with or without symptoms on diarrhea in the last year,and behaviors related to diarrhea,were collected through a self-designed questionnaire.Results The reported total prevalence of diarrhea symptoms in the last year was 17.6％ and,in urban areas as 16.8％,in rural areas as 18.2％ respectively.The differences on the reported prevalence rates of diarrhea in different age groups,background of education and occupations groups among urban residents were statistically significant (P＜0.05).Items as eating raw seafood or freshwater products,using the same chopping block and knife at the time when processing raw and cooked food,not being used to regular physical exercise etc.were the risk factors to diarrhea among adults from urban areas,with OR (95％CI) as 1.26 ( 1.07-1.48),1.37 (1.16-1.63) and 1.38 ( 1.20-1.59),respectively.The reported diarrhea prevalence rates related to sex,age,education background and occupations among rural residents did not show significant differences (P＞0.05).Without hand-washing habit before eating or after toilet-using,eating raw seafood or freshwater products,using the same chopping block and knife at the time when processing raw and cooked food,not being used to regular physical exercise etc.seemed to be the risk factors on diarrhea among adults in the rural areas with the OR(95％CI) as 1.85 (1.51-2.25),1.39 (1.17-1.67),1.44 (1.24-1.67) and 1.46 (1.27-1.67),respectively.Conclusion The prevalence reported on diarrhea symptoms among adults from the rural areas was higher than the urban adults.Diarrhea was related to health-related habits,eating habits and regularity of taking physical exercises.