With the objective to evaluate the efficacy and tolerance of artesunate in the treatment of noncomplicated falciparum malaria in endemic area of the State of Pará, 153 patients were randomized and studied in three groups, distributed by therapeutical scheme (I received mefloquine 1000 mg, II used artesunate 600 mg followed by mefloquine 500 mg). Evaluation was made by daily clinical and parasitological examination, in the first 7 days, and weekly until the 35th day of the follow-up. Biochemical and hematological analysts previously done and on the 7th day, targeting cure control and identification of possible effects related to drugs administration. As to sex, parasitemia and fever, studied groups were homogeneous. Time for parasitemia disappearance was shorter in the groups II and III respectively, whose therapeutical schemes had artesunate. Fever disappearance was quicker in the group treated with the combination of drugs. Clinical and biochemical alterations associated with drugs administration did not show significant differences among the studied groups. Early disappearance of fever and parasitemia, and absence of important side effects suggest that artesunate, isolated or administrated in combination with mefloquine, constitutes an able therapeutical procedure to constitutes and able therapeutical procedure to contribute for disease control in that region.