It is estimated that approximately 2.5 million cases of AIDS have occurred worldwide. HIV infected persons are estimated to be a cumulative total of 13 million, about 60% of whom have occurred in Subsaharan Africa. In this region, the risk of perinatal transmission is higher and the progression to AIDS is faster compared to Europe and the United States. We propose to conduct a randomized placebo-controlled trial to determine whether the administration of supplements of vitamin A alone or multivitamins excluding vitamin A to HIV positive pregnant women reduces the risk of perinatal transmission of HIV and whether the supplements slow the rate of progression of HIV infection in these women. The study will be carried out at the Muhimbili Medical Centre (MMC), Dar-es-Salaam, Tanzania among women who are pregnant for no more than 2O weeks at enrollment. We will recruit 960 HIV positive women. Potentially eligible women will be tested for HIV infection after obtaining their consent. Women will be randomly assigned in a 2x2 factorial design to daily use of vitamin A, multivitamins without vitamin A, both, or a placebo throughout the period of the study. At delivery, half the women will receive a large dose of vitamin A while the other half will be given a placebo. The health status of women and their children will be assessed by physicians and trained attendants at monthly visits to the study clinic. The viral load among HIV-infected women will be assessed using p24 antigen test. Levels of CD4/CD8 in a random sample of 400 women (100 in each group) will be measured at regular intervals. The diagnosis of HIV infection in infants will be done using a combination of tests that detect antibodies to the virus (IgG), that detect the virus itself (polymerase chain reaction)(PCR), in addition to clinical assessment. PCR will also be used to assess the time of transmission from mother to child. Fatal events will be ascertained by reviewing medical records and administering a standard verbal autopsy form. Dietary assessment of mothers and of children will be assessed using food frequency questionnaires. There is a great potential benefit to society if an adequate vitamin A and other vitamins status were found to slow progression to AIDS among HIV seropositive individuals or reduce the risk of perinatal transmission. These regimens would provide a simple and inexpensive intervention regimen that could be used in both developing and developed countries.