Aim. To estimate the prevalence of new-onset chronic obstructive pulmonary disease (COPD) and its clinical significance in patients with ST-segment elevation myocardial infarction (STEMI) on an electrocardiogram. Subjects and methods. The trial enrolled 154 patients with STEMI who underwent external respiratory function examination with a bronchodilatation test, as well as body plethysmography. The level of high-sensitivity C-reactive protein (CRP) was determined 10-14 days after the onset of clinical manifestations of STEMI. Results. Thirty-four (22%) of the 154 patients were known to have a history of COPD. Our examination was first to reveal irreversible postbronchodilatation airway obstruction and to diagnose COPD in 24 (20%) of 120 patients having no evidence of lung pathology in the history. All patients with new-onset obstructive pulmonary disease had varying degrees of respiratory symptoms before this hospitalization; however, they did not seek medical advice. The patients with STEMI concurrent with COPD were recorded to have lower diffusing lung capacity, higher CRP levels, more frequent recurrences of myocardial infarction, early postinfarction angina, but the incidence rate of pneumonia in in-hospital myocardial infarction achieved significant differences. Conclusion. The trial has disclosed that screening spirometry should be performed to detect COPD in patients with ischemic lung disease, which will be able to reduce the risk of complications and to improve prognosis in this patient group.