An ethnobotanical study was conducted in the Dakar area of Senegal to investigate the species used in the treatment of malaria. Seven plants are principally used: Cissampelos mucronata, Maytenus senegalensis, Terminalia macroptera, Bidens engleri, Ceratotheca sesamoides, Chrozophora senegalensis and Mitracarpus scaber. From a bibliographic study, it had been shown that the Cissampelos mucronata, Maytenus senegalensis and Terminalia macroptera have already been studied by several authors, and so only Bidens engleri, Ceratotheca sesamoides, Chrozophora senegalensis and Mitracarpus scaber were evaluated in the present study. For each plant, extracts were prepared with different solvents and tested in vitro on two chloroquine-resistant Plasmodium falciparum strains. Crude extracts from the leaves and the stems of Chrozophora senegalensis showed the best in vitro results. The IC(50) value of an aqueous extract of Chrozophora senegalensis was 1.6 microg/ml without cytotoxicity. The in vivo antiplasmodial activity of Chrozophora extracts was determined by both the oral and the intraperitoneal ways. The stages of Plasmodium cycle targeted by Chrozophora were then studied in vitro. These results could justify the traditional use of this plant in malaria treatment.