The aim of this study was to determine the prevalence of varicella IgG antibodies in the population of Catalonia, and the variables associated. The study was carried out in 2002 in a representative sample of juvenile (5-14 years) and adult population (> or =15 years) of Catalonia (Spain). The global prevalence determined by ELISA test was 95.5% (95% CI 94.7-96.3). The prevalence increased with age, from 82% (95% CI 77.0-87.0) in the 5-9 years age up to 99.4% (95% CI 98.2-100) in >64 years of age. No statistically significant differences in the seroprevalence according to the sociodemographic variables were observed. The current strategy of vaccinating preadolescents at 12 years of age who have not suffered the disease will require more than 30 years to cover the current gap immunity in adolescents and young adults. Vaccination with two doses of vaccine for all adolescents and adults < or = 50 years who report not having suffered the disease during childhood should be considered.