Objectives : To investigate the prevalence of cognitive impairment and dementia in elderly people, aged 65 or above, residing in Busan Metropolitan City. Methods : Total of 1,101 old people, aged 65 or above, living in Busan as of December 31, 2001 were selected using stratified three-stage cluster sampling. Cognitive impairment was determined from the MMSE-K score, and dementia confirmed from five psychometric measures and the Barthel index. The crude prevalence, sex-age adjusted for the Korean population, were obtained. Results : With the cut-off point for cognitive impairment was set at 24 points, or below, on the MMSE-K scale, the crude rate of cognitive impairment was 29.3% (15.7% for men and 37.5% for women), and the sex-age adjusted prevalence was 30.5% (17.5% for men and 37.0% for women). When the cut-off point for cognitive impairment was set at 20 points, or below, on the MMSE-K scale, the crude rate of cognitive impairments were 10.0% (4.1% for men and 13.5% for women), and 10.6% (4.7% for men and 13.1% for women), respectively. The crude dementia, and the sex-age adjusted rates were 7.4% (2.4% for men and 10.5% for women), and 8.0% (2.7% for men and 10.0% for women), respectively. Conclusions : The prevalence of dementia in this study was somewhat lower than that reported by other domestic and foreign studies. Our results related to the difference in time and space, diagnostic tools, response rates, and distribution of male and female subjects, etc.