Experience of application of extracorporeal ultraviolet irradiation of the blood (EUIB) in 60 patients with diffuse peritonitis of different etiology was presented. EUIB was conducted in 16-24 hours after performance of operation using apparatus MD--73 M "Izolda". The leukocytic index of intoxication after performance of the EUIB third procedure had reduced by 28.5%. Leukocytic index of shift had reduced after the first procedure performance--by 23.1%, after the third--by more than 50%. T-lymphocytes quantity in 22-24 hours after conduction of the first EUIB procedure had increased by 23.8% and after the third--by 63%. General postoperative mortality after complex treatment conduction using EUIB had constituted 3.3% and without EUIB--6.5%. Duration of treatment of the patients, in whom EUIB was applied, had shortened by 2.6 days.