The investigation has been performed on the isolated isovolumically contracting hearts of rats resuscitated after a 4-min clinical death caused by acute blood loss. It has been established that myocardial contractility disturbances, minimum during clinical death, become far more marked 30-60 min after recirculation and progress in the first 3 days, especially in unfavourable course of the postresuscitation period. Disturbed myocardial contractility closely correlates with enzyme release into the coronary flow and the efficacy of glucose utilization per unit of myocardial function. By day 7 contractility disturbances attenuate, mounting again two weeks later. Relative normalization of myocardial contractility is observed by the end of the first postresuscitation month, however, the release of enzymes from various cardiomyocyte ultrastructures into the coronary flow remains still high.