The aim of this short review is to draw attention to chronic obstructive pulmonary disease (COPD), a clinical syndrome associated with emphysema and/or chronic bronchitis, in the light of the current scientific knowledge. The reason is that COPD has high socio-economic costs and the most recent projections place it among the first causes of mortality and morbidity due to chronic disease. The nosography, the clinical picture, including the systemic manifestations, the pathogenesis and the pathophysiological mechanisms, with special emphasis on expiratory flow limitation and pulmonary hyperinflation, leading to the most relevant symptoms and signs of the disease, have been reviewed. Finally a brief analysis of the costs due to the disease is also provided.