Chronic obstructive pulmonary disease (COPD) is a major cause of death and disability worldwide. Recognition that the burden of this disorder will continue to increase over the next 20 years despite medical intervention has stimulated new research into the underlying mechanisms, leading to a rational basis for evaluation of existing therapies, and has suggested novel treatment approaches. Tobacco exposure remains the main but not exclusive cause of COPD. Whether the lung is injured by changes in the balance of proteases and antiproteases, tissue damage by oxidative stress, or a combination of the two is still not known. The genetic basis of susceptibility to COPD is now being studied as is the role of computed tomography in the identification of structural damage in individuals with less symptomatic disease. Clinical diagnosis still relies heavily on an appropriate history confirmed by abnormal spirometry. Smoking cessation is possible in a substantial proportion of individuals with symptoms but is most effective if withdrawal is supported by pharmacological treatment. Treatment with long-acting inhaled bronchodilators and, in more severe disease, inhaled corticosteroids reduces symptoms and exacerbation frequency and improves health status. Rehabilitation can be even more effective, at least for a year after the treatment. Recent guidelines have made practical suggestions about how to optimise these treatments and when to consider addition of oxygen, surgery, and non-invasive ventilation. Regular review of this guidance is important if future management advances are to be implemented effectively.