In the last 200 years or so, the recognition, diagnosis, and understanding of the pathogenesis of COPD have evolved considerably. Over the past few decades, various definitions of COPD and its "components" also have developed. Despite this, however, the treatment options for patients with this relentlessly progressive disorder are relatively limited. In the mid-19th century, the introduction of the spirometer yielded a powerful tool for the diagnosis of COPD. The currently available small, cheap spirometers hold great promise to help patients and their physicians closely monitor lung function. Early recognition of the close associations among emphysema and, more recently, small airways disease, and impaired airflow is discussed. This review also stresses the importance of the identification of COPD in its initial stages and the early onset of appropriate treatment. The therapy for COPD has changed in the last 40 years. Drug therapies in the 1960s included potassium iodide and ephedrine. Corticosteroids were not used, and oxygen therapy and exercise were actually contraindicated. Modern therapy for COPD is now more systematic and includes the use of bronchodilators and corticosteroids to improve airflow, in addition to oxygen therapy, pulmonary rehabilitation and, in selected patients, lung volume reduction surgery. The causal link between the chronic inhalation of tobacco smoke and COPD is beyond doubt, and smoking cessation remains the most important goal for patients. It is hoped that new, more effective therapies will soon be available for the treatment of this disabling disorder to provide improvement in symptoms and patient quality of life and to reduce or stop the rate of disease progression and mortality in patients with COPD.