PRIMARY OBJECTIVES of study: To compare the in vivo efficacy of artesunate-amodiaquine (ASAQ) versus artemether-lumefantrine (Coartem®) in a population of children aged between 6 and 59 months suffering from uncomplicated P. falciparum malaria. This will be expressed as the PCR genotyping corrected rates of parasite clearance as a measure of efficacy at day 42 after initiation of anti-malarial therapy (the correction is for recrudescence versus re-infection). This will provide the MoH with evidence for the most appropriate choice of ACT for this region. SECONDARY OBJECTIVES: - To measure the PCR uncorrected efficacy of both drugs at day 42 after treatment initiation - To measure the PCR corrected and uncorrected efficacy of both drugs at days 14 and 28 after treatment initiation - To calculate the proportion of early therapeutic failures, late clinical failures and late parasitological failures in a period of 42 days after treatment initiation - To formulate recommendations and to enable the Ministry of Health to make informed decisions about