In Afghanistan, studies over the past 15 years have shown a high degree of Plasmodium falciparum resistance to chloroquine (80%) and more recently an increasing degree of resistance to sulfadoxine-pyrimethamine monotherapy (12%). In 2003 the high failure rate of chloroquine against falciparum malaria led the national malaria treatment programme to switch its recommended first line drug treatment for uncomplicated Plasmodium falciparum malaria to artemisinin-based combination therapy (ACT) in the form of Artesunate/Sulfadoxine-Pyrimethamine (AS+SP). Second line drug treatment is oral quinine (7 days). The aim of this study is to conduct ongoing monitoring of the efficacy of the new combination against P. falciparum in a group of sentinel sites in Afghanistan.