In children born to human immunodeficiency virus (HIV)-infected mothers, factors that determine disease outcome and progression are unclear. Also, early diagnosis is hampered by maternally transferred antibodies. Children aged 0-24 months were retrospectively divided into two groups based on HIV seroreactivity or nonreactivity at age 15 months and analyzed for the presence of antibodies that mediate cellular cytotoxicity (ADCC) and virus neutralization. No difference was seen in the presence of these functional antibodies between groups. The persistently seropositive group was further divided into non-AIDS and AIDS groups according to clinical status at serum collection. The ADCC antibody frequencies were much higher (70%) in the non-AIDS group than in the AIDS group (30%). Of the non-AIDS children, 63% had neutralizing antibodies; no children with AIDS had these antibodies. HIV-specific ADCC and neutralizing antibodies do not seem to protect against transmission of HIV from mother to child but are significantly correlated with a better clinical stage of childhood HIV infection.