The efficacy of amodiaquine and sulfadoxine-pyrimethamine combination as a second-line therapy for chloroquine-resistant Plasmodium falciparum infections was investigated in Rwanda in September 1986. Children less than or equal to 5 years old presenting with a P. falciparum parasitemia 14 days after treatment with chloroquine were administered either amodiaquine (25 mg/kg over 3 days, 64 patients) or sulfadoxine-pyrimethamine (as a single dose with tablets containing 500 mg of sulfadoxine and 25 mg of pyrimethamine: 1/4 tablet for children under 1 year, 1/2 for those 1-3 years old, and 1 tablet for those 4-5 years old; 34 patients) and followed for 7 days. Seven days after starting treatment with amodiaquine, 50 (76%) children were aparasitemic. All the children who had received sulfadoxine-pyrimethamine were aparasitemic 7 days after initiation of therapy.