The development and spread of antimalarial drug resistance is hindering the control of Plasmodium falciparum malaria. Unfortunately, a vaccine will not be available for many years. Resistance to chloroquine, the most commonly used antimalarial drug, has been reported in practically all endemic countries. This resistance also affects most of the other antimalarial drugs, to different degrees. The problem is further aggravated by cross-resistance among drugs belonging to the same family. In recent years; failure of chloroquine prophylaxis and treatment of P. vivax infection has been reported in South-East Asia and South America. Antimalarial drug resistance leads to an increase in morbidity and mortality, especially among children. By analogy with tuberculosis and HIV infection, the accent is currently being placed on the use of antimalarial combinations in order to overcome the problem of multidrug resistance. Artemisinins are particularly good candidates for combination therapy.