 This is observational population pharmacokinetics study with a nested comparative bioavailability study.The study is intended to describe the variability in lumefantrine blood levels among under five year old Ugandan children with uncomplicated falciparum malaria receiving current standard artemether-lumefantrine dose regimens. Findings will form a basis for development of rational dosage recommendations. The nested comparative bioavailability study will explore effect of profiled local food intake maize porridge plus vegetable oil versus milk on lumefantrine uptake. As a strategy towards improved recommendations in resource limited countries during AL treatment in order to maximize the public health benefits. As a secondary objective we will correlate the variability in lumefantrine uptake to malaria treatment outcome and safety profile in this population. 