Dementia is a common problem facing all medical practitioners and it frequently results in hospitalization and death. This review provides a framework for dealing with dementia in clinical practice that is based on both traditional concepts and recent advances in the understanding of the problem. Distinguishing at the bedside between dementia and other disorders of intellect is emphasized. The main causes of dementia and their clinical characteristics are reviewed and a rational approach to definitive diagnosis is developed. Simple, effective symptomatic forms of therapy are described.