Chronic obstructive pulmonary disease (COPD) is defined as a disease that can be prevented and treated, characterized by limiting airflow, which is usually progressive and associated with an increased chronic inflammatory response in the airways and lungs to harmful particles or gases. The link between inflammation and chronic obstructive pulmonary disease is a subject of interest due to the multiple pathogenic effects. Although the mechanism of eosinophilic inflammation in the context of COPD has not been established firmly, the increased number of eosinophils has been associated with reduced lung function and increased risk of exacerbations in COPD patients. There is evidence that patients with exacerbations associated with serum eosinophilia at presentation responded better to oral corticosteroids, and increased blood eosinophils are predictive of future exacerbations of COPD. The clinical study was performed in a group of 100 patients with COPD GOLD II-IV in exacerbation. Patients w investigated clinically, paraclinically according to the 2016 GOLD and European Heart Failure (HF) guidelines. According to the COPD diagnostic spirometry data in the study group, patients with GOLD3 and GOLD4 severity o bronchial obstruction predominated: GOLD3 - 35 (35%), GOLD4 - 30 (30%) compared with those with GOLD2 - 24 (24%) and GOLD1 - 9 (9%) patients (both comparisons p<0.01, respectively). Analyzing the anamnestic, clinical and paraclinical data, the presence of the following risk factors in the studied group was established: smoking, chronic ischemic heart disease, high blood pressure, type II diabetes mellitus and obesity. Serum eosinophilia values were higher in patients with a more severe degree (GOLD3 - 2.5%, GOLD4 - 3.2%, p<0.05) and C, D types of (2.6% and respectively 3.2%, p <0.05) and those with NYHA functional classes I-II of the HF (3.2% vs 1.1%- HF III-IV NYHA, p<0.05). There was also a significant correlation between serum eosinophilia values and predictors of COPD severity, including indices of pulmonary function (FEV1) and number of exacerbations. Serum eosinophilia values were higher in patients with more severe grades and types C, D of COPD and those with functional classes I-II NYHA of heart failure and can be used in clinical practice to define patients with COPD who are at increased risk for a new exacerbation.