The pediatrician plays a key role in the prevention of mother-to-child transmission of HIV-1 infection. For infants born to women with HIV-1 infection identified during pregnancy, the pediatrician ensures that antiretroviral prophylaxis is provided to the infant to decrease the risk of acquiring HIV-1 infection and promotes avoidance of postnatal HIV-1 transmission by advising HIV-1-infected women not to breastfeed. The pediatrician should perform HIV-1 antibody testing for infants born to women whose HIV-1 infection status was not determined during pregnancy or labor. For HIV-1-exposed infants, the pediatrician monitors the infant for early determination of HIV-1 infection status and for possible short- and long-term toxicity from antiretroviral exposures. Provision of chemoprophylaxis for Pneumocystis jiroveci pneumonia and support of families living with HIV-1 by providing counseling to parents or caregivers are also important components of care.