The results of complex treatment of 81 patients with pyoinflammatory diseases with the use of blood ultraviolet irradiation are discussed. A marked clinical effect was noted, the terms of treatment reduced by 5-10 days, the outcomes improved, and the number of complications decreased. Irradiation of autologous blood by ultraviolet rays led to modulation of the indices of antimicrobial protection, increase of the intensity of the histochemical reaction to peroxidase up to 40-50%, and diminution of pH in the neutrophil phagosomes to 5.0. The ultrastructure and ability of thrombocytes to store serotonin were restored, and intensity of their metabolic processes increased, the membrane phospholipid composition changed, and juvenile platelet forms appeared.