Screening HIV infection in pregnancy provides an ideal opportunity to make an early diagnosis in women in order to provide treatment to reduce vertical transmission to the newborn. The objectives were to describe the profile of HIV-infected pregnant women attending municipal hospitals in Vitória and to identify the causes associated with the lack of HIV therapeutic prophylaxis. Descriptive analysis of antenatal and HIV surveillance data of pregnant women in Vitória, Brazil from 1997 to 2001 was performed. HIV infection was reported in 208 pregnant women. Their median age was 23 years, antenatal care was reported in 96.2% and HIV infection was diagnosed during antenatal care in 60.1%. Zidovudine (ZDV) therapy was initiated in 88% of the cases, 57.9% of which started before 20 weeks of gestation. The remaining 12% of the total of pregnant women received no therapy. Factors associated with lack of mother to child transmission (MTCT) prevention were: test not available (14 cases), delay of test result (seven cases) and patient's refusal to take medication (four cases). After delivery, 8.2% of the newborn did not receive ZDV and 14 women breastfed. Among the 196 live births, 3.1% (95%CI 1.9-4.3) of MTCT was reported. These data from an area with comprehensive HIV and antenatal surveillance provide an opportunity to identify gaps in public health efforts to reduce MTCT.