Whether administration of folic acid to children with malaria anemia is helpful is controversial. Therefore, we conducted a randomised, placebo-controlled trial of 14 days of treatment with folic acid (1 mg/d) in Zambian children with malaria anemia treated with either sulfadoxine/pyrimethamine (SP) or atovaquone/proguanil (AP). Among children who received SP, the prevalence of parasitemia was higher in children treated with folic acid than among those given placebo at days 3, 7, and 14 after the start of treatment, and the difference at day 3 was statistically significant (P = 0.013). Folic acid treatment had no effect on parasitemia in children treated with AP. Administration of folic acid led to a small increase in packed cell volume over that seen in the placebo group at days 14 and 28 after the start of treatment.