This study has been conducted for the purpose of identifying the levels of knowledge and attitude about dementia, and exploring the degrees of practice and the relationship among these variables in nursing assistants caring institutionalized demented elders. The subjects were 87 formal caregivers from 3 dementia-specialized nursing facilities, 2 dementia-specialized hospitals, 1 general psychiatric hospitals, and 3 general nursing homes. The data were gathered from July 10th to August 5th, 1998 through interviews by questionnaires. The measuring instruments of this study were developed by the researcher and proven for their reliability and validity. The collected data were analyzed using SAS program. 1) The lowest score among 6 sub-areas about practice showed on this subarea of maintenance of remained ADL function, offering stimuli and activities to demented elders was the second. 2) The third hypothesis of "the higher the attitude score they have, the higher the practice score they do" was supported (r=.370, p=.025). 3) The influencing factors significantly on knowledge were educational status, learning experience about taking care of patients, learning experience about dementia during last a year. 4) A factor of the period of taking care demented elders have significantly influenced on the attitude about dementia. 5) The influencing factors significantly on practice were age, marital status, learning experience about taking care of patients, learning experience about dementia during the last a year. 6) The most difficult situation the subjects perceived in taking care of demented elders was managing the aggressive and resistive behaviors of demented elders.