An estimated 800,000 children acquired HIV-infection in 2002, most as a result of mother-to-child transmission (MTCT), and vertically-acquired HIV infection continues to be of major public health importance. Prevention of MTCT is possible with a combination of interventions including antiretroviral therapy (ART) (usually in highly active combinations), elective caesarean section and avoidance of breastfeeding, and where infected women are identified before or in pregnancy and have access to these interventions, risk of MTCT is now below 1-2%. However, prompt identification of pregnant women with HIV infection remains pressing in many developed countries; additionally, concerns have arisen regarding adherence to complex treatment regimens in pregnancy and the potential impact of HIV drug resistance. More disturbingly, most HIV-infected women live in developing countries where many pregnant women even when tested do not return for their HIV results for a variety of reasons including stigma, and where most, if not all, strategies for prevention of MTCT have been of limited accessibility and / or feasibility. However, the Global Fund to Fight AIDS, Tuberculosis and Malaria, and other initiatives including pharmaceutical companies donation programmes and generic antiretroviral drug production have made prevention of MTCT in resource-poor settings an increasingly realistic goal, coupled with new evidence from clinical trials on the efficacy of abbreviated regimens of antiretroviral prophylaxis, including combination therapy, to prevent MTCT. Research is additionally focussing on reducing the risk of postnatal transmission through breastfeeding, with exclusive breastfeeding, early cessation and antiretroviral prophylaxis to breastfeeding women or breastfed infants under investigation. However, the key to prevention of paediatric HIV infections is adequate prevention of infection in women of reproductive age.