Vessels of the microcirculatory bed of the heart in myocardial infarction were studied on the basis of the material of 21 section observations using histological, histochemical methods and the technique of impregnation of films of the epicardium developed by V. V. Kupriyanov. In the ischemic stage in the zone of ischemia and in perifocal areas there were noted signs of increased vascular permeability and impairment of hemodynamics: plethora of the venous department of the microcirculatory system, stasis of the blood in capillaries, spasm and paresis of vessels of the microcirculation. In the necrotic stage in the zone of necrosis there were observed destruction of vessels of the microcirculatory bed; in the peri-infarction zone--drastic plethora of veins, venules and capillaries, higher vascular permeability, leucostasis, leucopedesis, perivascular cellular infiltrates, destruction of vessels of the microcirculatory bed, dilatation of lymphatic vessels; in the intact zone--venous plethora and elevated permeability. In cases of shocks and collapses in vessels of the microcirculatory bed of the heart beyond the zone of necrosis aggregations of erythrocytes were found. In the reparative stage newly formed vessels in the granulation tissue were observed; In the post-infarction scars sinusoid vascular cavities and arteries of the closing type were noted.