HIV (human immunodeficiency virus) is the leading cause of infant mortality in Africa where 1700 children are infected each day, principally by mother-to-child transmission. Prevention of this risk is therefore a public health priority. Considerable progress has been made in the past 10 years in preventing the risk of mother-to-child transmission in the peripartum period in Africa: short antiretroviral regimens during the third trimester of pregnancy can reduce transmission rates to less than 5%. Breast-feeding, which is widespread and prolonged in Africa, causes many HIV infections and thus reduces the efficacy of peripartum interventions. Interventions that offer alternatives to prolonged breast-feeding and are both socially acceptable and safe for the infant can effectively reduce the risk of postnatal HIV transmission. But operational implementation of these postnatal interventions remains complex. Use of antiretroviral agents as prophylaxis for mother and child during the breast-feeding period and clinical management of breast-feeding mothers with combined antiretroviral treatments offer hope that the risk of postnatal HIV transmission can be reduced, but the effectiveness and safety of these interventions still need to be assessed.