«No-reflow» phenomenon is the most striking example of myocardial reperfusion clinical failure. It is caused by a lack of adequate blood flow in tissues after successful recanalization of infarct-related artery and is of multifactorial nature. The main reason for «no-reflow» is microvascular damage, of both structural and functional nature. Microvascular microemboli formation is also of particular importance in developing this phenomenon. In patients with acute coronary syndrome undergoing thrombolysis, percutaneous coronary intervention or coronary artery bypass surgery, the risk for «no-reflow» is about 30% or more. In case of planned endovascular interventions, «no-reflow» prevalence ranges from 0.3 to 2%. Patients with «no-reflow» have highly increased risk of complications such as reduced systolic function, heart muscle remodeling, dilatation, cardiac chambers hypertrophy/hyperplasia, left ventricular aneurysm etc. In addition, «no-reflow» increases the risk of death. Predisposition for «no-reflow» might be associated with a number of local and systemic factors. For diagnosing this phenomenon, angiographic grading of coronary blood flow restoration (Thrombolysis in Myocardial Infarction - TIMI) and myocardial perfusion (Myocardial Blush Grade - MBG) is recommended. For the most accurate «no-reflow» diagnosis, different methods for myocardium visualization might be used. The most studied treatments of ongoing «no-reflow» are: vasodilators administered intracoronary (verapamil, adenosine, sodium nitroprusside) at percutaneous coronary intervention or coronary artery bypass surgery; systemic antiplatelet agents; mechanical protection from distal embolization. Given the multifactorial nature of the «no-reflow», further search for the novel methods for prevention and treatment of this phenomenon is needed.