In presenting the methods used by us in the treatment of malaria the writer feels that there exists a necessity at this time for a concise statement of exact methods which have been used successfully on a large scale since the comparatively recent advent of new antimalarial remedies. It is desired to present only the practical side of treatment as developed and used in the American Tropics during the past fourteen years, and recently used during a two year period in the medical care of 30,000 men, nearly all of whom had malaria. Accurate statistics and followup for determination of relapse rates are not available in this large group of cases treated. Inasmuch as most of the work was of a temporary nature and located in unsanitated regions, most of the cases of malaria when cured did not return to work. However, the labor law of the countries did not permit the laborer to be returned to his home until completely cured.