Varicella infections cause substantial morbidity and mortality in adolescents and adults. The primary infection, chickenpox, results in lifelong immunity to chickenpox. A seroprevalence study carried on adolescents 15-18 years of age attending schools in Lebanon showed 96.6% immunity to varicella. The positive predictive value for immunity to chickenpox based on history alone was 97.4%, whereas the negative predictive value was 4.5%. Coming from a bigger family was a statistically significant predictor of immunity to chickenpox. In a developing country like Lebanon the merits and limitations of implementing universal varicella vaccination is discussed in relation to seroprevalence and socioeconomic factors.