Vanicella (chickenpox) has long been considered a benign, inevitable disease of childhood. Complications are generally mild and rarely severe, and virtually every individual is infected by adulthood. Infection is associated, however, with a high risk of serious complications in certain high-risk groups, such as leukemic children. Concerns about the severity of varicella in this population have led to the development and testing of a live, attenuated vaccine. Because of the favorable results thus far available, the vaccine may soon be licensed for use in high-risk individuals. The fact that a vaccine may soon be available has led to an increased interest in the potential benefits of a childhood varicella vaccine program. The costs associated with varicella infection in normal persons without a varicella vaccination program have been estimated to be approximately $400 million, 95% of which is the cost of caring for a child at home. Vaccination of normal 15-month-old children with a safe and effective vaccine with long-lasting immunity could reduce the cost by 66% and result in a savings of $7 for every dollar spent on the vaccination program. This assumes that vaccine would be administered only once with measles, mumps, and rubella vaccine, that there would be no increase in the number of varicella cases in older persons who are at increased risk for complications, and that there would be no deleterious effect on the occurrence and severity of herpes zoster. If the assumptions cited above hold true, then it would appear that normal children would benefit from prevention of varicella by vaccination, not by virtue of the severity of the disease but rather because of the inevitability of the disease and its associated expense.