Studies undertaken in Spain indicate that 9% of the general population aged between 40 and 70 years is affected by chronic obstructive pulmonary disease (COPD). Although tobacco smoke is the causative factor in more than 90% of cases, it is estimated that only 10% to 20% of smokers develop COPD. This may be explained by the existence of genetic or environmental factors that modulate the toxic effects of tobacco. The best known genetic factor is alpha1-antitrypsin deficiency, which is associated with an increased risk of developing pulmonary emphysema in smokers. The most recent guidelines from both the World Health Organization and the American Thoracic Society/European Respiratory Society recommend the establishment of screening programs for the detection of alpha1-antitrypsin deficiency in patients with COPD. This strategy is crucial in Spain, where the disease is under diagnosed, mainly due to a low index of suspicion among doctors.