Prematurity increases the perinatal HIV transmission rate compared with term infants. There is sparse literature documenting the risk of transmission of HIV to extremely low birth weight (ELBW) infants.To determine the risk of perinatal transmission of HIV to ELBW infants in a tertiary neonatal unit in South Africa.A prospective database was maintained on all inborn ELBW infants over a 1-year period from March 2010 to February 2011. Survival and DNA HIV polymerase chain reaction results at 6 weeks were recorded.Of the 180 ELBW infants, 51 (28%) of these babies were HIV exposed. Of these 51 infants, 37 survived until 6 weeks of age. Polymerase chain reaction testing revealed 1 HIV-positive infant for a rate of 2.7% (95% confidence interval: 0.7-14.1%). Twenty-six (72%) of the 36 mothers received antiretroviral drugs, but only 16 (44%) had been treated for more than 1 month.The rate of HIV transmission in this cohort of ELBW infants is very low despite only 44% of the mothers receiving adequate antiretroviral drugs. We postulate that this is due to our high (89%) cesarean section rate, universal (100%) infant prophylactic antiretroviral drugs and the use of pasteurized breast milk.