The management of infants whose mothers are infected with the human immunodeficiency virus (HIV) involves minimizing the risk of vertical transmission of HIV, recognizing neonatal HIV infection early, preventing opportunistic infections, and addressing psychosocial issues. Maternal antiretroviral drug therapy during pregnancy and labor, followed by six weeks of neonatal zidovudine therapy, can significantly decrease the risk of vertical transmission. Additional antiretroviral drugs may be needed in some high-risk newborns. Elective cesarean section also may prevent vertical transmission of HIV. Virologic tests allow early diagnosis of HIV infection, facilitating the timely initiation of aggressive treatment and the prevention of opportunistic infections. Even when tests are negative, infants must be closely monitored until age 18 months to completely rule out HIV infection. Prophylaxis for Pneumocystis carinii pneumonia should be initiated when HIV-exposed infants are six weeks old and should be continued for at least four months, regardless of negative virologic tests, because P. carinii pneumonia is often the initial presentation of HIV infection in infants. Laboratory monitoring, screening for perinatal infections, appropriate social support, and other modifications of standard infant care are also necessary.