Aortic dissection is an acute lesion of the aortic wall accompanied by separation of the media due to rupture or intramural hematoma. The incidence rate of aortic dissection is 5 to 30 cases per million people a year. Acute aortic dissection is a highly lethal cardiovascular emergency with an incidence of 2000 new cases per year in the United States and 3000 in Europe. The mortality rate of aortic dissection is 3.2/100,000 per year. In case of sudden death of nonhospitalized patients, aortic dissection was proved in 1.5% of necropsy cases. Most of patients die within 48 hours after admission or 1.4% per each hour. The main clinical manifestations of aortic dissection are acute myocardial infarction, stroke, pulmonary embolism, acute heart failure, acute pancreatitis, mesenteries thrombosis, which mislead the physician. The main measure, which might reduce the mortality, is early diagnosis of aortic dissection. The standard diagnosis is based on clinical symptoms and verification by instrumental (imaging) methods. An alternative mean for diagnosis of aortic dissection might be the determination of concentration of smooth muscle myosin heavy chain protein in blood serum, the peak of which is found after 3 hours after the onset of pain. Normal value of smooth muscle myosin heavy chain protein concentration is 2.5 microg/L, while in case of aortic dissection it exceeds 22.4 microg/L. This diagnostic method has not been introduced in Lithuania yet.