Reduced sensitivity of Plasmodium falciparum to formerly recommended cheap and well-known antimalarial drugs places an increasing burden on malaria control programs and national health systems in endemic countries. The high costs of the new artemisinin-based combination treatments underline the use of rational and updated malaria treatment policies, but defining and updating such policies requires a sufficient volume of high-quality drug-resistance data collected at national and regional levels. Three main tools are used for drug resistance monitoring, including therapeutic efficacy tests, in vitro tests, and analyses of molecular markers. Data obtained with the therapeutic efficacy test conducted according to the standard protocol of the World Health Organization are most useful for updating national treatment policies, while the in vitro test and molecular markers can provide important additional information about changing patterns of resistance. However, some of the tests are technically demanding, and thus there is a need for more resources for training and capacity building in endemic countries to be able to adequately respond to the challenge of drug resistance.