The development of strategies to control malaria requires precise knowledge about the drug-resistant parasite levels and geographical distribution. Unfortunately currently available methods are not fully adequate for these parameters to be established. This paper describes the improvement of a radiometric micro-test to detect resistance to several drugs. This test is easy, rapid and permits analysis of numerous samples in a short time. A molecular assay is not currently available for the determination of resistance because the molecular mechanisms behind chloroquine, amodiaquine, mefloquine, quinine or halofantrine resistance remain obscure. Under these circumstances, we recommend the use of the modified microtest for them.