BACKGROUND:Smoking cessation is the most important therapeutic intervention in patients with chronic obstructive pulmonary diseases (COPD) and the health benefits are immediate and substantial. Major efforts have been made to develop methods with high smoking cessation rates. OBJECTIVES:To study whether a combination of spirometry and brief smoking cessation advice to smokers with COPD, annually for three years, increased their smoking cessation rate in comparison with groups of smokers with normal lung function. METHOD:Prospective, randomized study in primary care. Smoking cessation rates were compared between smokers with COPD followed-up yearly over a period of three years and smokers with normal lung function followed-up yearly for three years or followed-up only once after three years. RESULTS:The point-prevalence abstinence rate and prolonged abstinence rate at 6 and 12 months increased yearly and in smokers with COPD at year 3 was 29%, 28%, and 25%, respectively. The abstinence rates were significantly higher in smokers with COPD than in smokers with normal lung function. Smoking cessation rates among smokers with normal lung function did not increase with increasing number of follow-ups. CONCLUSION:Smokers diagnosed with COPD stopped smoking significantly more often than those with normal lung function.