Although the varicella-zoster virus infections are usually benign skin diseases, they can have serious systemic manifestations and complications. This article reviews the current concepts concerning the anatomy and physiology of the virus and the epidemiology, pathogenesis, pathology, immunology, and laboratory diagnosis of these infections. The information gained in these areas has improved our knowledge of the disease, permitted the detection of susceptible patients, allowed the earlier use of new antiviral treatment, and provided a background for the use of active and passive immunization. The clinical features and consequences of both varicella and herpes zoster are described. The prevention and treatment are underscored, especially with regard to the newer systemic antiviral therapy. Herpes zoster ophthalmicus is specifically detailed because of its frequency and because of serious ocular and systemic implications for both the dermatologist and the ophthalmologist. The nerve innervation of the eye and ocular adnexa as it pertains to herpes zoster ophthalmicus is outlined, and a description is given of the multiple ocular complications for the dermatologist. Data on the role of antiviral agents and of topical and systemic corticosteroids in herpes zoster ophthalmicus are presented. Postherpetic neuralgia, probably the most difficult management problem of herpes zoster ophthalmicus, is addressed from a descriptive, preventive, and treatment view.