Breast-feeding is of such critical importance to the general health of the infant, as well as the mother-infant relationship, that special efforts should be made to retain this practice even during the HIV pandemic. Breast-feeding is associated with lower rates of infant gastrointestinal infections and protects against high infant mortality from respiratory and gastrointestinal diseases. These protective effects are greatest in the first 6 months of life. However, HIV is transmitted through breast-feeding. HIV-infected women whose circumstances permit them a choice between breast- and formula-feeding have been encouraged to formula-feed. But in developing countries there are HIV-infected women who cannot afford to formula-feed or who, knowing the risks, choose to breast-feed. In these societies, HIV-infected women who deviate from the cultural norm of breast-feeding risk exposing their HIV status and becoming prey to negative social implications. For this group of women, defining strategies that can reduce their risk of transmitting HIV to their infants is essential. Based on data from previous studies, this study proposes to test the hypothesis that NVP will reduce breast-feeding transmission of HIV.