The authors report on three cases of severe P. falciparum malaria successfully treated by iv quinine and exchange transfusion. Serum concentrations of Tumor Necrosis Factor (TNF) were determined before and during treatment. After an initial decrease, serum levels of TNF remained markedly elevated during the first 48 hours despite exchange transfusion. Though exchange transfusion accelerates the elimination of parasites from the blood, it seems to have no immediate effects on reducing serum levels of cytokines such as TNF.