Varicella-zoster virus vaccine has diminished the consequences of chicken pox in terms of health and economical burden. The increasing number of doses administered worldwide has revealed rare but important adverse effects that had not occurred during clinical trials. We report here the case of an immunocompetent 3(1/2)-year-old girl who developed encephalitis and herpes zoster opthalmicus 20 months after her immunization with varicella-zoster virus vaccine. Molecular analysis confirmed the vaccine strain as the causative agent. After an intravenous course with acyclovir, the child made a full recovery with no neurologic sequelae.