Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality in adults and has important health economic consequences. Despite being such an important cause of health impairment, 1 the diagnosis of COPD is often made relatively late in the natural history of the disorder when there is already an appreciable fall in the forced expiratory volume in one second (FEV1) and symptomatic deterioration, as the early stages of the disease are relatively asymptomatic. COPD is formally defined by spirometric criteria according to the British Thoracic Society (BTS) guidelines on the management of COPD as a chronic slowly progressive disorder characterised by largely fixed airways obstruction (FEV1< 80% predicted and FEV1/FVC ratio of< 70% predicted). 2 However, we now know that COPD is a largely heterogeneous condition, consisting of a number of pathological processes whose eVects are modified by varied host susceptibility. 3 Some patients present with daily symptoms of cough and sputum production, suggestive predominantly of chronic airway inflammatory processes, that can make the diVerential diagnosis from bronchiectasis diYcult in clinical practice. Others complain predominantly of dyspnoea caused by the hyperinflation associated with the disease and may have a diVerent natural history from those producing sputum. Early studies showed little association between the hypersecretory and obstructive forms of COPD, 4 but other studies have shown positive relationships between chronic mucus hypersecretion and decline in FEV1. 5 Knowledge of the natural history of these diVerent processes and methods of diagnosis of COPD is still generally poor, making early detection of COPD patients problematical and identification of those who may be most susceptible to exacerbation and hospital admission particularly diYcult. Most patients who present with COPD in secondary care have a known diagnosis of moderate to severe COPD and spirometric parameters are usually measured either in the outpatient clinic or during a hospital admission. Although much recent emphasis has been placed on COPD in secondary care in view of the consequences of hospital admission, most patients with COPD are diagnosed and managed in primary care where many patients have mild COPD and diagnostic spirometric measurements are still limited in their use. Thus, the diagnosis of COPD in primary care will be mainly determined on clinical grounds rather than on formal spirometric criteria. As smoking cessation is currently the only intervention that can modify the natural history of COPD, 6 there is an urgency for early recognition and management of COPD in primary care to stop further irreversible changes in lung function.