This study was designed to evaluate early post partum rapid HIV testing of infants as surrogates for their mothers. In a screening of 971 infants whose mother's HIV-1 status was not known at delivery, 22 (= 2.26%) were found positive for antibodies by ELISA. Five were new cases and two (40%) were from transmitting mothers. This is in contrast with the UPR Women and Infants Transmission Study (UPR WITS) in which of 186 HIV-1 infected mothers none were transmitters. These were selected among thousands screened for anti-HIV-1 antibodies over a period of almost 5 years studied (September, 1996 through August, 2001). These results clearly indicate that all mothers at delivery should have a rapid test to determine their HIV-1 status to allow in the positive cases rapid intervention strategies to prevent perinatal transmission.