 This is a small detailed randomised open-label clinical trial comparing the efficacy of oral artemisone with oral artesunate in the treatment of uncomplicated falciparum malaria in Western Cambodia. A detailed pharmacokinetic-pharmacodynamic evaluation and in vitro sensitivity for the study drugs will be part of the assessments. The overall design and proposed conduct is very similar to the recently completed studies of high dose artesunate.Fever patients in the villages surrounding Pailin or equivalent study site in Western Cambodia will be screened with a PfHRP2-based malaria rapid test Paracheck by the village malaria workers. In case of a positive test result, the patient will be transported by the study team to the hospital, full consent as described above and enrolment procedures will be conducted. It will be made clear from the outset that refusal to participate will in no way jeopardize subsequent antimalarial treatment.Eligibility can only be confirmed by a medically qualified investigator. Subjects who fulfil all the inclusion criteria and have none of the exclusion criteria will be randomised to one of the three treatment arms according to the randomisation schedule. Subject numbers will be will be assigned when the subject is enrolled after screening and prior to randomisation.Patients will be randomized in blocks of 15 to receive either artemisone 4 mgkgday for 3 days plus mefloquine 15mgkg on day 3 and 10mgkg on day 4 N50 or artesunate 4mgkgday for 3 days plus mefloquine 15mgkg on day 3 and 10mgkg on day 4 N25. 