One hundred thirty-eight adult patients with acute Plasmodium falciparum malaria were randomized to receive either beta-arteether or alpha/beta-arteether. The drugs were administered in the dose of 150 mg once a day intramuscularly for three consecutive days in hospitalized patients. After one week of hospitalization, patients were followed-up for three weeks after release from the hospital. There was no statistically significant difference between cure rates, mean fever clearance time (FCT), mean parasite clearance time (PCT), and occurrence of side effects in either group. The cure rate was 97.14% for beta-arteether and 97.01 for alpha/beta-arteether (P = 0.9660). The mean PCT was 38.49 hours for beta-arteether and 36.90 hours for alpha/beta-arteether (P = 0.6054), and the mean FCT was 37.27 hours for beta-arteether and 37.9 hours for alpha/beta-arteether (P = 0.8718). Both arteether formulations were safe and efficacious in reducing the clinical symptoms of acute falciparum malaria. There was also rapid clearance of parasitemia with both formulations. Thus, either beta-arteether or alpha/beta-arteether can be used in the treatment of acute falciparum malaria.