A detailed evaluation of 2 different artesunate containing regimens in patients with uncomplicated malaria will be performed. Patients will be randomised to receive either a) Artesunate 2mg/kg/day for 7 days or b) Artesunate 4mg/kg/day for 3 days plus mefloquine 15mg/kg on day 3 and 10mg/kg on day 4 The effect on parasite clearance and cure will be assessed in relation to blood concentrations of the antimalarial drugs ('PK-PD').