Abstract. Thoraco-abdominal and transmediastinal injuries are the most challenging injuries faced by surgeons. Aim. To acquaint medical practitioners with a clinical case of diagnosis and treatment of a rare variant of damage to the right internal thoracic artery in a thoraco-abdominal injury. Materials and methods. We present a clinical case of a rare variant of damage to the right internal thoracic artery in a thoraco-abdominal injury, which was complicated by a massive hemothorax, shock and DIC syndrome. Results. The work presents data on the examination and treatment of a patient with a thoraco-abdominal stab wound. A preliminary diagnosis was established: thoraco-abdominal stab wound on the right, hemorrhagic shock. The diagnosis was established based on the patient's complaints, medical history, physical examination data, available at the time of the examination, the results of laboratory and instrumental research methods. Damage to the liver, diaphragm, and internal thoracic artery was established intraoperatively. Clinical interest is not only the rarity of this injury - injury of the internal thoracic artery, but also the therapeutic and diagnostic tactics. Conclusions. We consider this case interesting and instructive. Each wound should be evaluated from the point of view of possible injury of large vessels, in the projection of which location it is localized. The primary surgical treatment of the wound should be carried out under the strict control of an experienced surgeon, especially if the wound is located in the projection of a large vessel. The integrity of the vessel and the absence of bleeding must be confirmed! Intraoperatively, any finding should be taken into account, correlated with possible injuries, and interpreted clinically (provide a logical explanation that satisfies the clinical situation). The decision regarding treatment tactics should be made by the operating surgeon (or a board of surgeons), immediately based on the clinical situation. The surgeon must be reactive and flexible, and have the ability to quickly change the approach according to the findings.