Objectives: The aim of this study was to establish the most common comorbidities among subjects in a group of patients with COPD undergoing treatment in Clinical Hospital Centre Osijek, how many comorbidities subjects have on average, and whether they are connected with the characteristics of the underlying disease. Study design: Cross-sectional study. Patients and methods: The subjects are patients of both sexes with COPD diagnosis who have had regular check-ups and treatment in outpatient clinics of KBC Osijek Pulmonary Institute from 2018 to 2020. Data on the characteristics of a disease retrieved from case histories have been analysed, including comorbidities. Other methods deployed include spirometry, bioimpedance, the 6-minute walk test, and questionnaires (the mMRC Dyspnea Scale, CAT questionnaire, BODE Index and The Charlson Comorbidity Index). Results: Research has been conducted on 40 patients with the average age of 67, out of which 68 % were men and 33 % women. 88 % of the subjects have been diagnosed with the presence of at least one comorbidity. The median number of present comorbidities is 2. The most common comorbidities are hypertension (63 %), GERD (25 %), depression (20 %) and obesity (18 %). The results show that significantly more, according to statistics, osteoporosis affects patients belonging to risk group D (p = 0,02). Another statistically significant difference referring to comorbidity between different groups of patients according to the mMRC degree of Dyspnea, GOLD degree of obstruction, ABCD risk groups and groups according to BODE Index, has not been found. Conclusion: The most common comorbidities among patients are hypertension, GERD, depression and obesity. On average, patients have two comorbidities. Osteoporosis has been found in a statistically more significant percentage in patients in group D who have a lot of symptoms and exacerbations. Other comorbidities were evenly represented in patients suffering from diseases of all severity levels and disease characteristics.