As Korea is one of the fastest aging countries in the world, the management of dementia has become a major social issue. An ideal way of treating dementia is to prevent the onset of the disease, as effective cure remains elusive yet. Therefore, every effort is needed to provide any interventions to delay the progression of dementia. Comprehensive assessment of dementia includes evaluation of cognitive functions, activities of daily living and neurobehavioral symptoms. Detailed history from the family member or the caregiver is essential and standardized assessment tools are recommended when evaluating a patient's functions. By putting all the information together, we estimate the severity of the disease and the prognosis to set up a therapeutic plan. As the incidence of dementia is on the rise, it is advisable for all members of rehabilitation medicine team to be well-acquainted with the assessment methods of dementia for early identification of problems and the monitoring of therapeutic interventions. This article provides a brief overview of the assessment of dementia to assist clinicians in evaluating and treating these patients.