Varicella is an acute infectious disease common during childhood. It has mostly an uncomplicated course in early childhood. Neverthless, it may result in severe complications, especially in particular age groups and clinical conditions. Down Syndrome represents a risk factor for developing complications, because of the frequent comorbidities and their immunodeficiency. A 2-year-old white Caucasian female affected by Down Syndrome was referred to our hospital for cardiac arrest in course of varicella disease. After cardiopulmonary resuscitation and stabilization, her clinical conditions didn’t improve and she developed a massive pulmonary hemorrage, which led her to exitus. Mortality due to varicella infection is rare, but it is more common in subjects with immune deficit or chronic pathologies, and in particular age-groups. The importance of the vaccine for preventable infectious diseases is stressed in this paper, in which we present a case of death in an unvaccinated cardiopathic child with Down Syndrome affected by varicella.