Esenbeckia febrifuga (Rutaceae) is a plant traditionally used to treat malaria in the Brazilian Amazon region. Ethanol extract of stems displayed a good antiplasmodial activity against Plasmodium falciparum strains W-2 (IC(50) 15.5+/-0.71 microg/ml) and 3 D7 (IC(50) 21.0+/-1.4 microg/ml). Two