Currently, veterinary specialists are increasingly using blood transfusion in various pathological conditions of the animal body. But at the same time, the effect of hemoconservatives on the body of animals and whole blood has been little studied. The review article provides an analysis of the results of studies of post-transfusion complications in the period from 2008 to 2022. Particular attention in these studies was paid to the frequency of occurrence, the quality of blood or its component, the compatibility of the donor and recipient, complications during and after hemotransfusion. Post-transfusion reactions that can occur as a result of blood transfusion have shown a number of possible immunological and nonimmunological reactions of the organism of animals and humans, the origin of which has been little studied. Posttransfusion reactions of the body include incompatibility reactions, reactions to erythrocyte proteins, reactions to platelets and leukocytes during plasma transfusion, anaphylactoid reactions, hypothermia, heparinization, coagulopathy and thrombosis, microbial contamination, hyperammonemia, hypophosphatemia, hyperkalemia, acidosis, pre-transfusion hemolysis, hemosiderosis. The frequency of occurrence of these reactions has not been sufficiently studied, since mainly isolated cases or studies with a small sample are described. The problem of post-transfusion reactions in animals in our country began to be studied recently. Post-transfusion reactions are practically not monitored, since this requires additional research in a hospital veterinary clinic.