Falciparum malaria continues to be an important health problem on the American continent. Although transmission is now mainly confined to geographic zones lying between latitudes 15 degrees N and 15 degrees S, there has been a resurgence of the disease during the past decade in many parts of the Region. It has occurred in countries where the transmission of malaria had previously been interrupted and in countries where intensive antimalarial activities are in progress, as well as in countries where vigorous antimalarial efforts are not being pursued. In the XXX Report on the Status of Malaria Programs in the Americas, presented at the XXI Pan American Sanitary Conference held in Washington, DC, in September 1982, four main reasons were given for the deteriorating malaria situation: 1. Technical problems associated with the development of vector resistance to insecticides and of Plasmodium falciparum resistance to 4-aminoquinoline drugs. 2. Problems encountered with intensive inter- and intracountry movement of people. 3. Problems of shrinking resources caused by rising personnel, equipment, and supply costs. 4. Problems related to sociopolitical and human factors. The objectives of this workshop were to review the status of falciparum malaria in the different regions of the American continent, to indentify constraints to effective control of the disease, to review current knowledge regarding drug resistance in falciparum malaria, and to identify appropriate measures and research projects that would improve the epidemiological assessment and control of falciparum malaria in various areas of this continent. - Introduction.