Naturally occurring antibodies to polysaccharide antigens of pathogens commonly isolated from HIV-1-infected subjects were analyzed in serially collected sera of children born to seropositive mothers. Purified polysaccharides from type 14 Streptococcus pneumoniae, group C Neisseria meningitidis, type b Haemophilus influenzae, glucomannoprotein from Candida albicans and diphtheria toxoid antigens were used in an ELISA test to assess antibody levels. A significant rise of anti-pneumococcus antibody titres was noticed both in HIV-1-infected and in non-HIV-1-infected children aged 18 months or more. Anti-C. albicans and anti-group C N. meningitidis antibodies were elevated only in HIV-1-infected children older than 12 months. Anti-type b H. influenzae antibodies remained at low titres in both groups. Anti-diphtheria toxoid antibodies, analyzed as a model of humoral response to a protein antigen, were similar in both groups of HIV-1-infected and noninfected children.