The purpose of this study was to explore the knowledge and attitude of dementia care among nursing assistants in long-term care facilities. This design of this study was cross-sectional with stratified random sampling conducted in Taipei and New Taipei City. A battery of questionnaires included dementia care knowledge and attitude as well as demographic information. A total of 271 questionnaires were obtained; most assistants had adequate dementia care knowledge; however, ＂definition＂, ＂progression＂ and ＂daily care＂ of dementia were relatively insufficient. The knowledge score of nurse assistants who work in long-term care facilities was significantly higher than those who work in nursing homes. Nurse assistants who received education in the past or on-the-job training of dementia care, or who had experience in caring for persons with dementia have better knowledge about dementia care. Nurse assistants' attitude toward dementia care was neutral to positive. Findings revealed that nursing assistants who have more positive attitude toward persons with dementia had better knowledge of dementia. Together our findings suggest that content regarding dementia care should be included in the training course as well as on-the-job training of nursing assistants working in long-term care facilities. It can not only enhance the competence of nurse assistants but also increase the quality of care in long-term care facilities regarding dementia care.