Chronic obstructive pulmonary disease (COPD) is common and often undiagnosed in its early stages, especially in smokers, who are also most at risk. Patients can develop severe or very severe disease before they consult a physician. It is therefore important to identify patients at-risk of COPD and check their lung function regularly since early stage disease is often asymptomatic or mistaken for asthma. Primary care physicians are often the first health care providers to encounter patients with COPD in the early stages, and their role in early detection and treatment process is pivotal. Spirometry is a cheap, simple and reliable method for the early detection and monitoring of COPD patients, and for establishing a differential diagnosis. Spirometry gives immediate results and communicating the results to smokers has been shown to motivate them to quit. Early diagnosis and appropriate therapy can positively influence disease course, slowing progression, relieving symptoms and reducing the incidence of acute'flares', or exacerbations.