Alzheimer's disease is the leading cause of mental impairment in elderly people, accounting for a large proportion of admissions to nursing homes and assisted living homes. Psychiatric symptoms associated with Alzheimer's disease, although common, have not received much attention until recently. In this review the authors discuss in detail the association between Alzheimer's disease and delusions. Definitions of terms are followed by an overview of the classification, clinical epidemiology, etiology, treatment, and prognosis of delusions in Alzheimer's disease. The article concludes by highlighting some of the open questions regarding delusions in Alzheimer's disease.