The objective of this study was to describe the clinical courses of infants born to human immunodeficiency virus (HIV)-infected mothers in Taiwan. Eleven children, including 1 set of twins, born to 10 HIV-infected mothers were included in the study. HIV antibodies were assayed and HIV-1 polymerase chain reaction (HIV-PCR) or virus cultures were performed; HIV infection was established when there were at least 2 separate positive results of HIV-PCR or culture. Three sets of primers detecting LTR-gag, pol and env were used. The viral load of HIV RNA was measured and used as an indicator of the treatment response. Two of the children were HIV-infected and received combination therapy, including 2 kinds of nucleoside analogue reverse transcriptase inhibitors plus 1 protease inhibitor. Neither of these children exhibited HIV-related symptoms or signs during the study period. Both mothers of the infected children were Taiwanese and their HIV infection status was not known during pregnancy. In contrast, HIV infection was found in early pregnancy in the 4 women living in Taiwan who were from other countries, all of whom received prophylactic therapy. The other 4 mothers who did not transmit the infection to the infant were Taiwanese, 3 of whom were known to be HIV-seropositive during pregnancy. Based on these results, the vertical rate of transmission was 18% (2/11). Early detection of HIV-infected pregnancy is vital to reduce the incidence of HIV-infected births.