Smoking cessation is the most effective way to reduce the risk of developing chronic obstructive pulmonary disease (COPD). It prevents or delays the development of airflow limitation and also reduces its progression. The objective of this study was to systematically review the effects of interventions for smoking cessation in people with COPD. Comprehensive searches of electronic and internet databases were carried out from 1966 to March 2002, using the Cochrane Airways Group search strategy. The reference lists of all selected randomized trials and relevant reviews were inspected for additional published reports and citations of unpublished research. We evaluated the efficacy of behavioural interventions (e.g. counselling), pharmacotherapy (nicotine replacement therapy and non-nicotine therapy such as bupropion), and combinations of both. The main clinical outcome measure was prolonged abstinence after at least 6 months, confirmed by a biochemical test. Five trials comprising 6491 patients with COPD were included. Results of the Lung Health Study show that, by using an intensive behavioural (relapse prevention) programme combined with nicotine replacement therapy, prolonged abstinence rates are not only significantly higher compared with no intervention, but the difference in efficacy was sustained for over 5 years. A 12-week treatment course with bupropion sustained release combined with individual counselling, however, did not result in significantly higher prolonged abstinence rates after 12 months. Present evidence suggests that the most effective intervention for prolonged smoking cessation in patients with COPD is the combination of nicotine replacement therapy, coupled with an intensive, prolonged relapse prevention programme.