The authors report some failures of chemoprophylaxis and curative treatment of Plasmodium falciparum and Plasmodium vivax malaria. These infections were contracted in the area of the cambodian-thaï border by 8 Europeans treated by various regimens and 34 Cambodians treated by quinine. In the latter group, the quinine failure rate in Plasmodium falciparum infections was about 47% (RII or RIII?) and 17,5% in Plasmodium vivax. Total cure of vivax malaria with usual doses of Primaquine among the Europeans, failed in 3 out of the 6 treated patients. Morphological particularities (abnormal pigment, lack of Schüffner dots) were noticed in these Primaquine resistant vivax strains. A possible relation is considered between Primaquine resistance and these morphological particularities.
