Herpes zoster disease and its most common complication, postherpetic neuralgia, are associated with significant morbidity in the elderly. The zoster vaccine boosts cell-mediated immunity to varicella-zoster virus, the virus that causes both varicella and herpes zoster. This vaccine has demonstrated the ability to reduce the zoster-related burden of illness and the incidence of both zoster and postherpetic neuralgia in a randomized, controlled trial conducted in individuals aged 60 years and older, an age group at increased risk of herpes zoster. Widespread use of this vaccine could prevent as many as a quarter of a million cases of zoster disease each year. The design and outcomes of the Shingles Prevention Study, which examined the efficacy and safety of the vaccine, and the rationale for widespread immunization against varicella-zoster virus, are presented here.