A total of 52 patients with myocardial infarction have been examined. The patients have been subjected to HBO procedures. 40-62 min sessions with a working pressure of 0.3-1.1 atm were performed. The optimal pressure during the first days is 0.3 atm with a gradual increase to 0.7 atm. It is important to prepare the patient before the session with the end in view to achieve hemodynamic normalization and pain relief and to ensure a possibility of coronarolytic intake during the session. By session 4-5 hypercapnia and hypoxia, hyperventilation syndrome were eliminated, hemodynamic and respiratory parameters normalized, and immunity recovered. Only in one case a session had to be interrupted because of pulmonary edema recurrence. In 7 patients usual complications which were easily relieved have been observed. HBO shortened the patients' stay in an intensive care unit by 1.6 days and decreased lethality by 9.5%.