Chloroquine remains the most commonly antimalaric drug utilized all around the world (340 t in 1988). Its efficiency is linked to its action on the digestive vacuole of plasmodium. Since 1957, the areas of resistance are spreading over of an alarming way, striking all continents. 3,000 cases of malaria are imported in France each year, and 90% of the strains tested in vitro by incorporating tritium hypoxanthine are resistant to chloroquine. The resistant parasites are able to exclude chloroquine from their cytoplasm and produce in great number two genes to synthetize a glycoprotein, probable agent of cellular exclusion of the antimalaric drug. Despite of it, to prescribe chloroquine in prophylaxis remains indispensable, because the risk of severe malaria due to some sensitive strains of Plasmodium falciparum.