Smokers are more prone to developing chronic obstructive pulmonary disease (COPD) than non-smokers. This knowledge comes from studies spanning 10 years or less. We used data from The Copenhagen City Heart Study to determine the 25-year absolute risk of developing COPD in healthy individuals. The 25-year incidence of moderate and severe COPD was 20.7% and 3.6%, respectively. Smoking cessation, especially early in the course of the follow-up, decreased the risk substantially. The absolute risk of developing COPD among smokers is at least 25%, which is higher than previously anticipated.