BACKGROUND: Cigarette smoking remains the single largest cause of premature death in the United Kingdom. As part of the government's national service framework for coronary heart disease, smoking cessation forms a key part of the strategy. OBJECTIVES: To determine the effectiveness of bupropion treatment for smoking cessation in a general practice setting, measuring continuous abstinence from smoking, from 8 weeks to 52 weeks. DESIGN: Prospective observational study. SETTING: One general practice (six whole time equivalent doctors, 11,070 patients) in rural Northumberland. SUBJECTS: Of the 243 patients who presented to the practice over a one year period for smoking cessation, a total of 227 motivated people, who were appropriate for bupropion treatment as a pharmacological aid for smoking cessation, entered the study. Continuous smoking cessation at one year was validated by an exhaled carbon monoxide level of 10 ppm or less. RESULTS: Fifty patients successfully gave up smoking, giving a one year smoking cessation prevalence with bupropion of 22% (95% confidence intervals (CI) 17% to 28%). There was no difference in success rate for sex, number of cigarettes smoked, the number of years smoking, or whether there were other smokers in the household or not. CONCLUSION: Bupropion treatment in this general practice helped 22% of motivated people to quit and remain stopped smoking at one year. Mainly nurses, whose prescribing rights are restricted and currently exclude bupropion, deliver smoking cessation services in primary care.