Several recently published randomized trials have demonstrated that a substantial proportion of the mother-to-child transmission of HIV-1 can be prevented by antiretroviral therapy late in gestation and at delivery to mother and infant. The cost implications of these findings are considerable for resource-poor settings. Preliminary data also suggest very low rates of transmission among mothers receiving maximally suppressive combination drug regimens. Prophylactic cesarean delivery has also been shown to reduce transmission in women not receiving antiretroviral agents, and may play a role in selected patients. The avoidance of breast feeding with infant formula supplementation is clearly protective against HIV-1 transmission, but may not improve infant survival in some poorer settings because of associated increases in other infectious diseases and malnutrition.