By the investigation of our study group 595 HIV infected pregnant women have been confirmed in Japan since 1984. In recent years, around 40 pregnant women a year were diagnosed as HIV positive. These HIV infected pregnant women were not concerned with a value of CD4 and received antiretroviral therapy such as zidovudine (AZT) monotherapy or highly active antiretroviral therapy (HAART) starting from the second trimester of pregnancy. According to recommendations and current data, cesarean delivery before the onset of labor is performed around 37 weeks of pregnancy and prophylactic AZT syrups are given to infants starting 8-12 hrs after birth for 6 weeks. These preventive managements such as antiretroviral therapy, elective cesarean delivery and formula feeding significantly reduced mother-to-child transmission (MTCT) of HIV. The transmission rate of HIV fell to 0.5% in Japan, but the problem of the teratogenicity of antiretroviral drugs remain unclear. Further studies are needed.