There are a variety of complications related to chronic hemodialysis treatment, including thrombosis in hemodialysis access leading to blood recirculation, and in turn to the deterioration in hemodialysis effectiveness. Given that ozone decreases blood viscosity, increases erythrocyte deformability, and inhibits coagulation, the periodic blood ozonation may be of benefit in the attenuation of these disturbances. To gain insight into this issue,we originally evaluated the impact of ozonated autohemotherapy on recirculation in arteriovenous fistula, hemodialysis adequacy, and the frequency of dialyzer reuse. Twelve chronically hemodialyzed patients with peripheral arterial disease were enrolled in the prospective, placebo-controlled study. Nine sessions of autohemotherapy with the exposure of blood to oxygen, as a control, and nine sessions of autohemotherapy where the blood is exposed to ozone in a concentration of 50 microg/mL are administered in a single-blind manner. Access recirculation is measured by means of spectral technology(Crit Line Monitor, HemaMetrics, Kaysville, UT, U.S.A.), and hemodialysis adequacy is calculated using the Daugirdas formula and expressed as the Kt/V index. The Kt/V index and the frequency of dialyzer reuse do not change after ozonated autohemotherapy. Recirculation decreases after ozonotherapy in the majority of patients.on average by 35.3%, but the change does not reach the level of statistical significance (P = 0.064). We demonstrate that ozonated autohemotherapy does not influence dialysis adequacy and the frequency of dialyzer reuse. The improvement of fistula function, expressed as a decrease in recirculation, is not significant, although seen in the majority of patients.