The functional metabolic activity of neutrophilic leukocytes underwent clinical laboratory assessment in tropical malaria. A significant inhibited acUvity of myeloperoxidase and decreased levels of cationic protein, glycogen, and lipids were revealed while the activities of alkaline and acid phosphatase were increased. The degree of changes in the enzymatic activity of leukocytes and the level ofintra-leukocytic components depended on both the stage of the disease and the degree of the pathological process and the presence of mixed infections. The maximum changes in the content of all components of the neutrophilic microbicidal system were noted in patients with tropic malaria concurrent with typhoid fever. The values of the peripheral neutrophilic microbicidal system may be used as additional criteria for evaluating the severity and prognosis of tropical malaria.