Infection with Plasmodium falciparum malaria remains a significant cause of morbidity and mortality in malnourished children. Malnutrition is known to have a modulating effect on the incidence of malaria infections, its severity and effectiveness of treatments. However, little data exists on antimalarial drug efficacy in malnourished children. Artesunate-amodiaquine combination is the first line treatment used in Médecins Sans Frontières programmes in Niger. The assumption of current efficacy of artesunate-amodiaquine is based on non malnourished children. The aim of this study is to measure the clinical and parasitological efficacy in severely malnourished children.