Chronic obstructive pulmonary disease (COPD) is defined by fixed airflow limitation associated with an abnormal pulmonary and systemic inflammatory response of the lungs to cigarette smoke. The systemic inflammation induced by smoking may also cause chronic heart failure, metabolic syndrome and other chronic diseases, which may contribute to the clinical manifestations and natural history of COPD. Thus COPD can no longer be considered a disease only of the lungs, as it is often associated with a wide variety of systemic consequences. A better understanding of the origin and consequences of systemic inflammation, and of potential therapies, will most likely lead to better care of patients with COPD. Medical textbooks and clinical guidelines still largely ignore the fact that COPD seldom occurs in isolation. As the diagnosis and assessment of severity of COPD may be greatly affected by the presence of comorbid conditions, the current authors believe that lung function measurement, noninvasive assessment of cardiovascular and metabolic functions, and circulating inflammatory markers (e.g. C-reactive protein) might help to better characterise these patients. Similarly, preventive and therapeutic interventions should address the patient in their complexity.