In Tanzania, 1075 HIV-1-infected pregnant women received either no micronutrients, vitamin A, multivitamins excluding vitamin A or multivitamins including vitamin A in a randomized, double-blind, placebo-controlled trial. Among women assigned multivitamins, 30 fetal deaths occurred compared with 49 among those not on multivitamins. Multivitamin supplementation decreased the risk of low birth weight (LBW) by 44%, severe preterm birth by 39%, and small size for gestational age (SGA) at birth by 43%. Vitamin A supplementation had no significant effect on these variables. Multivitamins, but not vitamin A, resulted in a significant increase in CD4, CD8, and CD3 counts. The results suggested that multivitamin supplementation is a low-cost way of substantially decreasing adverse pregnancy outcomes and increasing T-cell counts in HIV-1-infected women.