We observed 70 male patients with a seriously proceeding Chronic myocardial ischemia. They were hospitalised because of frequent, permanent and serious attacks of stenocardia at rest and in stress situations. More than 2/3 of these patients had suffered from a myocardial infarct. In the course of two weeks an intensive therapy with all modern preparations for vasodilatation was made. This therapy proved to be unsuccessful. Nearly all patients were administered more than 10 tables of nitroglycerin per day and, in addition, they were injected analgetics as a compensation of attack. The ultraviolet own blood irradiation (UVB) had a positive therapeutic effect in all patients. There was a good success in 46 patients, in all patients satisfactory results could be registered. The effect of therapy was evident by the decrease of administration of nitroglycerin required, by an increase in the degree of stress capacity, and by an easier treatment of stenocardia attacks. The observation time for patients amounted to 2-8 months. The success of therapy remained in 38 patients. After this time the success of therapy could partially be regained by a repeated number of irradiation series. Then, it remained positive in 9 of 22 patients who had been followed-up for 10 months. The half decay period of eliminating 131I from an intradermal depot could be normalised under the influence of ultraviolet own blood irradiation. This ultraviolet own blood irradiation had no significant influence on the fibrinogen level, fibrinolytic activity, and erythrocyte aggregation (examined in 11 patients). A 2 1/2-fold diminution of monomer fibrin complexes in the blood could be observed. The titre of antistreptolysin-O was increased in all patients who had got over the infarct. It had completely normalised a week after finishing the ultraviolet own blood irradiation. Spectroscopic examinations of the blood and plasma made after ultraviolet own blood irradiation revealed that this irradiation will not only affect the properties of Hb, but will also cause a photochemical transformation accompanied by a destruction of some plasma proteins, of the membrane of formed blood elements, and a photosynthesis of biochemically active compounds. The mechanism of action of ultraviolet own blood irradiation is complicated and requires further exact investigations. Even today, however, this method can be recommended as a complex therapy in patients with severe myocardial ischemia.