COPD is a disorder characterized by expiratory flow limitation that does not change markedly over periods of several months' observation. When the diagnosis is suspected, COPD patients should be submitted to full assessment and initiation of therapy. Initial assessment includes a complete history, a detailed physical examination, pulmonary function tests, a chest X-ray, and blood tests. Therapy of COPD aims at reducing symptoms, preventing exacerbations and preserving optimal lung function. Many COPD patients have a bronchospastic component and usually show some response to bronchodilator therapy. Anticholinergics, beta 2-agonists or theophylline are used as monotherapy or in combination. A subgroup of patients with COPD may benefit from oral long-term corticosteroid therapy. At prime diagnosis of COPD, a trial of oral steroid under optimal bronchodilator therapy is warranted in order to identify steroid responders early in the course of the disease. Stopping smoking is the most effective preventive measure and should be combined with complementary approaches such as eviction of environmental irritants, vaccines and prescription of antioxidants. Long-term oxygen therapy is beneficial in chronically hypoxemic patients. Respiratory rehabilitation uses a multidisciplinary approach aiming at decreasing dyspnea, increasing exercise tolerance and improving quality of life. Nocturnal home noninvasive mechanical ventilatory assistance can improve arterial blood gas tensions in patients with respiratory failure, but the long-term effect on survival is still under investigation. In selected patients, surgery (bullectomy, lung volume reduction, lung transplantation) may greatly improve pulmonary function.