This study investigated anti-dengue serotype-specific neutralizing antibodies in a random sample of dengue IgG-positive individuals identified in a survey performed in a hyperendemic setting in northeastern Brazil in 2005. Of 323 individuals, 174 (53·8%) had antibodies to dengue virus serotype 1 (DENV-1), 104 (32·2%) to DENV-2 and 301 (93·2%) to DENV-3. Monotypic infections by DENV-3 were the most frequent infection (35·6%). Of 109 individuals aged <15 years, 61·5% presented multitypic infections. The force of infection estimated by a catalytic model was 0·9%, 0·4% and 2·5% person-years for DENV-1, DENV-2 and DENV-3, respectively. By the age of 5 years, about 70%, 30% and 40% of participants were immune to DENV-3, DENV-2 and DENV-1, respectively. The data suggest that infection with DENV-1, -2 and -3 is intense at early ages, demonstrating the need for research efforts to investigate dengue infection in representative population samples of Brazilian children during early infancy.