Abstract: Objective To investigate the prevalence and distribution of chronic diseases among middle aged and elderly community residents in urban Shanghai.Methods Two corss-sectional community-based surveys among 6 488 men aged 40-74 years and 8 511 women age 40-70 years were conducted in Shanghai Changning district in 1998 and 2003,respectively.Standardized prevalence of chronic diseases was estimated based on gender and age structure of whole population from the census in 2000.Mantel-Haenszel chi-square was used in the analyses.Results Hypertension ranked the first in both men and women with the age-adjusted prevalence rates of 28.0% and 22.6%.There were 40.9% of the men and 36.5% of the women had at least one of the 5 main chronic diseases(diabetes,hypertension,coronary heart disease,chronic obstructive pulmonary disease,and stroke) during their lifetime.The residents with higher body mass index had higher prevalences of hypertension and coronary heart disease.The prevalences of stroke,hypertension,and chronic obstructive pulmonary disease were higher in the men with frequent smoking or alcohol drinking,but not in women.Conclusion There were differences in the prevalences of common chronic diseases for the residents of sub-group in the community,and obesity control and to stop smoking are important interventions among middle aged and elderly residents in community.