Systematic database searches identified 435 antimalarial drug treatment trials, involving 82,616 patients, conducted and published between 1966 and December 2002. Of these trials 72% were randomised; 64 (15%) trials involved severe malaria, 47 (11%) studied Plasmodium vivax, 3 Plasmodium malariae or Plasmodium ovale, and the remainder (74%) assessed treatment responses in uncomplicated falciparum malaria. Twelve trials (2.7%) specifically evaluated antimalarial treatments in pregnant women. Overall 49% of trials were conducted in Asia (29% from Thailand alone) and 42% in Africa. Half of all the patients studied had been in trials published in the past 7 years. There has been a recent rise in the proportion of trial enrolling children, and a tripling in the average number of patients recruited per trial (from approximately 100 in the 1970s to 300 currently). Chloroquine was given to over half the patients in antimalarial drug trials (n = 53552) compared with artemisinin derivatives (n = 12463), mefloquine-sulphadoxine-pyrimethamine (n = 9153), mefloquine (n = 5546) and sulphadoxine-pyrimethamine (n = 5909). The quality of safety and efficacy data for recently evaluated drugs contrasts with a relative paucity of data for older 'established' compounds.