The results of randomized trials among men and nonpregnant women have confirmed the potential benefits of vitamins B, C, and E supplements on the immune status of human immunodeficiency virus (HIV)-infected individuals. Larger trials are needed to ascertain whether these benefits are sustained and to examine the effect of supplementation on clinical outcomes. Among pregnant women, vitamin A supplements increase the risk of mother-to-child transmission. Supplementation with vitamins B, C, and E during prenatal and breastfeeding periods should be encouraged, in light of the protective effects on adverse pregnancy and child outcomes. In children aged >6 months, vitamin A supplements are beneficial for reducing morbidity and mortality in developing countries, including among HIV-infected children. There are no data on the relationships of other micronutrients and child health. For adults and children, more research is warranted on the role of selenium, zinc, and other trace elements on various measures of health among HIV-infected individuals.