We assessed the effect of maternal human immunodeficiency virus (HIV) infection on birth outcomes and infant survival in rural Mozambique. Pregnant women attending the antenatal clinic were recruited. These women and their infants were followed-up for one year. Birth outcomes were assessed at delivery and infant HIV status was determined at 1 and 12 months of age. Women positive for HIV were more likely to have anemia at delivery than women negative for HIV (51.3% versus 35.4%; P < 0.001). Infants born to HIV-positive mothers had a significantly higher post-neonatal mortality rate than infants born to HIV-negative mothers (7.8% versus 1.9%; P < 0.001). The rate of transmission of HIV by breastfeeding during the first year of life was 15.1% (95% confidence interval = CI 7.6-22.4). Assessment of the impact of HIV infection on birth outcomes in rural Africa is essential for tailoring public health measures to reduce mother-to-child transmission of HIV and excess infant mortality.