Malaria associated with complications or a fatal outcome is caused by Plasmodium falciparum. The mortality due to this disease is parallel to the degree of parasitemia. Successful use of exchange blood transfusion as a therapeutic adjunct for this infection was reported. The rationale for this form of therapy is based on (1) rapid reduction in parasite load by exchange transfusion, (2) removal of toxic substances and (3) reducing microcirculatory sludging. We describe here thirteen cases of severe falciparum malaria treated with infusion of quinine dihydrochloride and exchange transfusion 2,320-8,000 ml of whole blood. We observed that the greatest reduction in the average circulating infected red blood cells, from 20.7 per cent to 9.3 per cent, seemed to occur early in the first 2,000 ml of blood exchange and the parasitemia often reduced to 5.1 per cent in patients who had 4,000 ml of blood exchange. In order to reduce the initial parasitemia to 5 per cent by exchange transfusion, we suggest the volume of exchange transfusion should be 2,000 ml for average parasitemia 10 per cent, 4,000 ml for parasitemia > 20 per cent and 2,000-4,000 ml for parasitemia 10-20 per cent.