Forensic medical practice shows that the death of a person can be accompanied by blood loss, which is the result of an injury, or a manifestation of a disease, and therefore, during the forensic medical examination, it is necessary to establish a causal relationship between it and the cause of death. In order to solve these issues, the results of the autopsy, histological examination, analysis of clinical and laboratory hematological data, as well as morphological changes in the heart muscle play a leading role.
 Aim of the work. Forensic-medical substantiation of the cause of death and features of establishing a cause-and-effect relationship with blood loss in injuries and diseases.
 Materials and methods. The material of the study was cases of death due to injuries and diseases accompanied by the development of blood loss, which were analyzed in accordance with the instructive forensic and clinical materials.
 Results. Severe injuries to the human body are accompanied by the development of blood loss, the consequences of which can cause a shock reaction. Clinically, the body's reaction to blood loss occurs when more than 15 % of BCC is lost, and severe shock develops in case of blood loss of more than 25 % of BCC, which is approximately 1,25-1,5 liters of blood. In addition, the speed of blood loss is also important, as a result of which the body's protective mechanisms do not have time to compensate for it. In the case of forensic substantiation of acute blood loss as the cause of death, autopsy and histological examination data are usually used. However, blood loss of varying degrees can also accompany a number of diseases, as a result of which the body develops anemia with hypoxia, which affects the state of the cardiovascular system. In such cases, blood loss does not directly lead to death, but causes disorders in the function of the heart, in particular, exacerbation of the course of coronary disease. This pathogenetic mechanism indicates the absence of a direct causal relationship between blood loss and the onset of death. In such cases, to justify the cause of death, it is necessary to pay attention not only to the presence of clinical indicators confirming blood loss, but also to laboratory hematological data – the content of erythrocytes, the amount of hemoglobin, hematocrit, and most importantly – morphological changes of the heart, which must be described by the most thorough way
 Conclusions. Complex analysis of all morphological changes and findings during examination of corpse, clinical symptoms of diseases, results of gradual hematological investigations are used to estimate the cause of death. To avoid occurrence or exacerbation of the course of the ischemic heart diseases the monitoring of function of the cardio-vascular systems and electrocardiography in patient with blood loss as symptom of diseases should be used in clinical practice.