Alzheimer's disease is a leading cause of dementia with a multifactorial and still barely understood etiology. A growing body of epidemiologic and experimental data support a role for infectious agents in this process; herpes simplex virus 1 (HSV-1), in particular, is a strong suspect. We briefly summarize the data pointing at a pathogenic role for HSV-1 in the development of Alzheimer's disease and review results indicating that antiviral might be beneficial in the therapy of this condition.