Aim. To study the effectiveness of monafram during percutaneous coronary intervention in patients with acute coronary syndrome in critical state. Material and methods. The results of emergency intervention were analyzed in 1794 patients with acute occlusion of the culprit artery, multifocal lesions of the coronary arteries. There were 2 equal groups of 794 patients each. In the 1st (main) group, Monafram was used before percutaneous coronary intervention; in the 2nd (control) group, the drug was not used. The efficiency of coronary blood flow reestablishment was evaluated according to the method of assessing the number of coronarography frames, when the revascularized artery was filled with a contrast agent: complete reestablishment of coronary blood flow was noted up to 20 frames, from 20 to 40 it was partial, and over 40 the coronary flow was not reestablished. The number of thrombotic complications after the intervention was recorded. Results. In group 1, coronary blood flow was completely reestablished in 56.7% of patients, partially — in 43.6%, and it was not reestablished in 0.7%; in group 2, in 46.4%, 51.9% and 1.7% of patients respectively. Thrombotic complications developed in 1.3% of patients in the 1st group, and in 4.5% of patients in the 2nd. Thrombosis did not develop when coronary blood flow was reestablished completely; it occurred in 0.2% when reestablished partially and in 61.9% of patients — when it was not reestablished. Conclusion. Monafram is highly effective in the prevention of the thrombotic complications development in critically ill patients.