Background: There is increasing evidence that low birth weight (LBW) is associated with poor health conditions during neonatal period, infancy and in adult life. It is possible that some form of fetal growth restriction occurs in babies of HIV sero-positive women. Aim: The study was aimed at determining the effect of maternal HIV infection on neonatal birth weight and other anthropometric indices. Methods: The study was prospective cohort in design. The study group consisted of 100 consecutive HIV sero-positive pregnant women receiving care at the antenatal clinic of University of Nigeria Teaching Hospital (UNTH) Enugu, Nigeria. The control group consisted of HIV negative women matched for age and parity. Primary outcome measure was the prevalence of low birth weight amongst newborn of HIV sero-positive women.