The 2 largest maternity hospitals in Bangkok implemented comprehensive programs to prevent mother-to-child HIV transmission in 1998. We conducted a cross-sectional survey of post-partum HIV-infected women in 1999 through 2001 to evaluate these programs. Women were given structured interviews at 0 to 3 days, 1 month, and 2 months postpartum. Medical records of women and their newborns were reviewed. Of 488 enrolled women, 443 (91%) had antenatal care: 391 (88%) at study hospitals and 52 (12%) elsewhere. The HIV diagnosis was first known before pregnancy for 61 (13%) women, during pregnancy for 357 (73%) women, during labor for 22 (5%) women, and shortly after delivery for 48 (10%) women. Antenatal zidovudine (ZDV) was used by 347 (71%) women, and intrapartum ZDV was used by 372 (76%) women. Twelve (55%) of the 22 women who first learned of their HIV infection during labor took intrapartum ZDV. All 495 newborn infants started prophylactic ZDV; the first dose was given within 12 hours for 491 (99%) children. Ten (2%) children were breast-fed at least once by their mother, and 10 (2%) were breast-fed at least once by someone else. Although uptake of services was high, inconsistent antenatal care, fear of stigmatization, and difficulty in disclosing HIV status prevented some women from using services.