OBJECTIVE Aim: The aim of the research is to study the immunohistochemical markers of the endothelium of blood vessels and myocardial ventricles under chronic exposure to sodium bichromate and lindane, as well as in conjunction with damaging biochemical agents contained in the blood. METHODS Materials and Methods: The object of the experiment was outbred white mice (males). The study was carried out in 3 groups: 1st group - control, 2nd group - exposure to sodium bichromate 5 mg/kg, 3rd group - exposure to organochlorine pesticide lindane 100 mg/kg. In this experiment authors used the next methods: immunohistochemical method., biochemical research, statistical analysis. RESULTS Results: The data obtained from an experimental study show that the level of cardiomarkers in blood plasma is characterized by different changes when exposed to these two compounds. Basically, the predominance of the effect of sodium bichromate on the LDH level is noted as compared to the effect of lindane; on the CK-MB level, their effects were the same, i.e., there is an increase in their level in blood plasma. CONCLUSIONS Conclusions: Thus, long-term exposure to sodium bichromate leads to the activation of angiogenesis, destruction of the integrity of the endothelium, and this, in turn, leads to reparative changes located around in the myocardial cells.