NVP has several properties that make it an attractive candidate for antiretroviral therapy to interrupt HIV-1 transmission in the intrapartum and early post-partum period. The pharmacokinetic profile suggests that NVP would be rapidly absorbed and transferred to the infant in utero when given during labor and delivery. The HIV-1 antiviral activity is rapid with significant reduction in plasma virus occurring within a few days of drug administration. In addition, NVP has been shown to penetrate cell-free virions and inactivate virion-associated RT in situ. This property would be potentially useful in inactivating cell-free virions in the genital tract as well as in breast milk. These characteristics of NVP suggest that treatment of an HIV-infected pregnant woman in labor with an oral dose of NVP may provide a prophylactic level of NVP in the infant during the time of exposure to virus in the birth canal and/or maternal blood. In addition, NVP may inactivate the virion-associated RT present in cell-free virions in the genital tract or breast milk.