Pharmacologic therapy for patients with COPD is aimed at both achieving relief of symptoms and altering the progression of the disease. Since the principal symptom of COPD is breathlessness, symptomatic management is aimed at controlling this symptom and involves the use of a wide variety of bronchodilator drugs. The mechanism of action, chemical properties and rationale for use of these medications will be discussed in this chapter. Several pharmacologic strategies have been developed with the aim of inhibiting the progression of the disease. Unfortunately to date the results of these studies have largely been disappointing and so the pharmacology of these agents is not discussed in detail. In addition to these broad classes of agents other therapies such as oxygen, antibiotics and nutritional agents are also widely used in the management of patients with COPD; the rationale for the use of these agents is discussed elsewhere in this book.