Herpes simplex virus (HSV) is a member of the herpesviridae family. Recognised since ancient Greek times, the virus frequently infects human beings, causing a range of diseases from mild uncomplicated mucocutaneous infection to those that are life threatening. In the past 50 years, substantial advances in our knowledge of the molecular biology of HSV have led to insights into disease pathogenesis and management. This review provides a contemporary interpretation of the biological properties, function, epidemiology, and treatment of HSV diseases.