The purpose of this study is to determine the correlations between problematic behaviors and activities of daily living(ADL) targeting 106 demented elderly people hospitalized in a geriatric hospital. To examine the cognitive function of the subjects, the study used Korean Mini Mental State Examination(K-MMSE). For problematic behaviors and ADL, the study collected data based on Patient Assessment Forms in the geriatric hospital. Among problematic behaviors, apathy/indifference had the highest correlation with the items of ADL. Irritability/lability, agitation/aggression, depression/ dysphoria, night-time behavior and wandering also showed to be correlated to items of ADL(p<.05). This study demonstrated that cognitive function, problematic behaviors and ADL of the demented elderly hospitalized in the geriatric hospital are correlated to each other.