Aim To study the relationship between severities of the carotid artery injury and the atherosclerotic process in coronary arteries of elderly patients with acute coronary syndrome (ACS).Material and methods The study included 110 patients aged >75 years. Based on the degree of maximal carotid stenosis according to data of duplex scanning (DS), all patients were divided into group I, (>50% stenosis) and group II (<50% stenosis).Results According to coronary angiographic data, multivessel disease was observed in 63.6 % of patients. Patients of group I more frequently had three-vessel coronary artery disease than patients of group II (35.8 and 5.3 %, р<0.001). Coronary angiography and DS showed that 82.7 % patients (in group II, not all carotid stenoses were hemodynamically significant) had a combined damage of coronary and carotid arteries; carotid artery stenoses of >50% were associated with three-vessel coronary artery disease. A correlation between atherosclerosis of carotid and coronary arteries was found. Considering this correlation, a scale was introduced that suggested the severity of coronary atherosclerosis based on DS of carotid arteries. The score was assigned by assessing the degree of maximal stenoses in carotid arteries. A ROC analysis has determined a threshold score suggestive of the severity of coronary atherosclerosis: score <6, absence of >70% coronary stenosis; score >6, likely presence of >70% coronary stenosis (sensitivity, 70 %; specificity, 89 %).Conclusion Combined coronary and carotid artery disease was detected in 82.7% of elderly patients with ACS. A correlation between the severity of atherosclerosis in carotid and coronary arteries was found. DS of carotid arteries can be extensively used in evaluation of elderly patients with ACS, which will allow additional stratification of patients at high risk of cerebrovascular and recurrent cardiovascular diseases.