In order to assess the prevalence of the functional disability defined by activity of daily living (ADL) and instrumental activity of daily living (IADL) and associated factors in elderly Chinese, a population-based cross-sectional study was performed in urban, plain rural and mountain rural regions of Beijing. Of the 3440 subjects, 1707 are males and 1733 are females, with mean age of 71.4+/-7.7 years. Demographic, socio-economic and health aspects were obtained by trained interviewers. The results showed functional disability prevalence was 6.5% on ADL and 7.9% on IADL. Among the three representative areas in Beijing, the plain rural had the highest disability rate, increasing with the progression of age. Bathing and doing heavy housework were the two most difficult functional tasks. The functional disabilities were associated with gender and marital status. Our data suggest that plain rural elderly are most likely to generate functional disability, and bathing and doing heavy housework are two promising predictors to monitor the development of functional disability in the elderly.