Prevention of malaria in pregnancy is critical given the high incidence of malaria in Zambia and its serious impact on both maternal and infant survival. Intermittent presumptive treatment with sulfadoxine-pyrimethamine has been shown to be highly efficacious for reducing the risk of malaria in pregnancy. However, based on a study done in western Kenya, HIV-infected pregnant women may need more frequent dosing of SP, i.e., on a monthly basis rather than the standard 2-dose regimen given during the second and third trimesters, as HIV appears to reduce the effectiveness of the SP drug combination. The goal of this study was to evaluate the efficacy of the standard dosing regimen in comparison to an intensive monthly SP dosing schedule in HIV-positive women.