Chronic obstructive pulmonary disease (COPD) is a progressive disease of the respiratory system, characterized by chronic and reversible or irreversible airflow obstruction. COPD is one of the most common causes of morbidity and mortality worldwide, and it represents a significant public health problem. One of the characteristics of COPD is systemic inflammation that indicates that COPD isn’t a disease that only affects the respiratory system, but also has significant and measurable systemic effects that increase morbidity of disease. Comorbidities are common in patients with COPD and they have a significant impact on prognosis. The most common and most serious of them are cardiovascular and cerebrovascular disease, lung cancer, diabetes, cachexia, muscle weakness, osteoporosis, anxiety and depression, pulmonary infections, anemia, gastroesophageal reflux disease and pulmonary embolism. Smoking is an important risk factor of COPD and most of comorbidities. Cardiovascular disease is the most common and probably the most important comorbidity in patients with COPD. Studies showed that incidence of cardiovascular disease was significantly higher in patients with COPD then in those who don’t have disease. Energy deficit and reduced muscle mass are poor prognostic factors and they have a significant impact on the survival, specially in severe COPD. The incidence of osteoporosis in these patients is two to five times higher than in the general population, but it is very often underdiagnosed. The presence of COPD and respiratory infections can lead to a vicious circle. Infections can cause an occurrence of exacerbations and decrease in lung function, and reduced lung function is a risk factor for the development of new lung infection. It is important to be careful with corticosteroid therapy in exacerbation because it can increase the risk of lung infections. There is an alarming increase in incidence of lung cancer in patients with COPD which requires screening tests in predisposed patients. Also there is a need for screening tests for depression. In addition, COPB patients usually have normocytic and normochromic anemia.