A prospective study was done to determine the age specific prevalence of antihepatitis A antibodies (anti HAV Abs) among children in Delhi. Four hundred and twenty children aged 0-12 years attending outpatient department for vaccination or any minor illness were studied. Sera was tested by ELISA for anti HAV Abs using a commercial kit (Hepvase A 96 TMB). Thirty samples of cord blood were similarly analyzed. All samples of cord blood were positive for anti HAV Abs. Prevalence of anti HAV Abs was 80% by 5 years of age. The most vulnerable age group was 0.5-1.5 years (anti HAV Ab positivity). Cord blood had 100% positivity. Univariate and multivariate analyses taking anti HAV antibody positivity as dependant variable demonstrated that age and father's education (socioeconomic status) significantly affect prevalence of anti HAV Abs. Sex, water supply, history of jaundice in self or family did not have any significant effect on anti HAV antibody positivity. Prevalence of anti HAV antibodies is 80% by 5 years of age. Further studies in different strata of society and different regions in the country are required to assess the need and age for vaccination.