Purpose: This study was performed to assess the degree of cognitive function of elderly by MMSE-K performances and of that effect. Method: The subjects were 185 aged over 65 in Daejeon Metropolitan city. Data were collected through personal interview using the questionnaire from 10 to 31, Jan. 2003. The measures were Korean version of Mini-Mental State Examination(MMSE-K). Results: The mean score of MMSE-K was $22.60{pm}5.39$. The prevalence of cognitive impairment was estimated as 48.6% by MMSE-K ${leq}23$ and significantly age, gender, and education effect. The subtype score of MMSE-K were significantly lower in female group in each items : orientation in time and place, attention/calculation, language except registration and recall. And the scores were significantly lower in the older group and non-educated group in the all items of MMSE-K. Conclusion: Gender, age, and education showed significant effects on total and subtype MMSE-K score. Cognitive function decline were higher in female, older age group, and non-educated group. Therefore, those three factors are thought to be one of important risk factors for development of dementia, also it is assumed to be affected by other variables than age, gender, education effect.