In 1994, data were published on the effectiveness of zidovudine in preventing perinatal transmission of HIV infection. Using data from surveillance projects in San Antonio, Dallas, and Houston, Texas, U.S.A., we linked records of children born from 1987 through 1996 with records of their HIV-infected mothers. Prenatal care was measured by Kotelchuck's Adequacy of Prenatal Care Utilization (APNCU) Index. We examined the association between adequacy of prenatal care and four measures of zidovudine prescription: prenatal, intrapartum, neonatal, and the complete regimen. Inclusion criteria was that the mother's HIV infection was diagnosed before a live birth; 221 mother-infant pairs were included in the analysis. Overall, 68% received inadequate or no prenatal care. Over time, the proportion of mother-infant pairs with adequate prenatal care doubled (24%-48%; relative risk [RR], 2.0; 95% confidence interval [CI], 1.3-3.0), and the proportion prescribed prenatal zidovudine tripled (20%-67%; RR, 3.4; 95% CI, 2.4-4.9). In logistic regression, APNCU (adjusted odds ratio [aOR], 2.6; 95% CI, 1.1-6.2) and time period (aOR, 19.9; 95% CI, 8.1-48.7) were associated with prenatal prescription of zidovudine. The benefits of prenatal care, including HIV testing and zidovudine treatment, underscore the urgent need to improve access to and use of prenatal care services.