Mother-to-child transmission of human immunodeficiency virus type 1 has become rare in developed countries, with the use of highly active antiretroviral treatment, elective cesarean section, and avoidance of breastfeeding. In the developing world, however, these interventions are unfeasible, and cost-saving methods for prevention of vertical transmission are vital. Prevention begins with voluntary counseling and testing, improved maternal education and access to prenatal care. Various antiretroviral drugs administered before, during, and for short periods after delivery have decreased vertical transmission. Where safe and compliant formula feeding is difficult, avoidance of mixed feeding may improve infant outcomes. However, post-natal transmission via breast milk remains a major challenge. As we continue to find cost-effective answers to protect infants worldwide, the search for a HIV-1 vaccine continues.