The purpose of the cost-benefit analysis described in this article is to determine the economic value of vaccination of healthy children against varicella in France. It is based on the results of two specific investigations--an epidemiological model and a prospective observational study (1832 cases studied) of the socio-economic consequences of varicella. This cost-benefit analysis was conducted from the viewpoint of the society and that of the patient, for vaccination coverage rates ranging from 10 to 90%. This analysis demonstrates the value of varicella vaccination when associated with measles-mumps-rubella (MMR) vaccination: if varicella and MMR vaccines are co-administered, the vaccination of 80% of the children against varicella leads to a reduction in medical costs associated with varicella including that of vaccination, ranging from 10 to 77% according to the values adopted for vaccination costs, varicella treatment costs, discount rate and vaccine efficacy. The results of this study also underline the benefits of a vaccination policy that aims to achieve a high rate of coverage, thereby reaping the highest benefit from vaccination, and also avoiding potential negative consequences.