Malaria has become an increasingly common health problem in the 1970s and 1980s, both in areas where infection is endemic and in travellers returning to non-endemic areas. The severity of infection varies widely, depending on the plasmodial species involved, and there is an extensive chemotherapeutic armamentarium currently available to combat malarial infection. Drug chemistry, pharmacokinetics, mechanism of drug action and resistance, and toxicities are outlined for the cinchona alkaloids (quinine and quinidine), chloroquine, amodiaquine, pyrimethamine, the sulphonamides, pyrimethamine/sulfadoxine, mefloquine, pyrimethamine/sulfadoxine/mefloquine, the sesquiterpene lactones, primaquine, and other drugs. A knowledge of the distribution of drug resistance is vital for the provision of effective antimalarial therapy, and current information in this area is outlined. Chloroquine remains the mainstay of treatment for the erythrocytic stages of Plasmodium vivax, P. ovale, P. malariae, and chloroquine-sensitive P. falciparum malaria. The dormant hepatic stages of P. vivax and P. ovale also require further treatment with primaquine. Quinine, alone or in combination with other drugs, is the primary agent used to treat chloroquine-resistant falciparum malaria. Falciparum infection can rapidly become fatal, therefore its complications of multiple organ failure, heavy parasitaemias, cerebral malaria, and hypoglycaemia must be recognised and managed promptly. Because these protozoal parasitic infections are now encountered throughout the world and can become life-threatening, a wide variety of practitioners must become more familiar with their correct treatment.