AIM. This survey set out to determine the factors associated with outcome of unaided smoking cessation attempts and to compare the characteristics of smokers who had tried to stop with those who had never tried. METHOD. A postal questionnaire was sent to a random sample of 2000 adults in Aberdeen, Scotland. Those respondents who smoked or who were ex-smokers were sent a second questionnaire. The outcome measure for success in trying to stop smoking was abstinence for more than four months. RESULTS. Light and heavy smokers were more successful at smoking cessation than moderate smokers. Those who succeeded perceived that they had more social support than failures, and were more likely to have 'simply just stopped'. They were less likely to have used nicotine gum or to believe that smoking was harmful. Those who failed experienced more withdrawal symptoms, and were more likely to be tempted by the presence of others smoking. Eleven per cent of smokers had never tried to stop. These smokers were older and more dependent than those who had tried to stop. They were less likely to acknowledge the health risks of smoking or to conform to social pressures, but were more likely to consider stopping for financial reasons alone. CONCLUSION. Heavily dependent smokers may fare better in unaided cessation than the results of clinic-based research suggest. For those who have tried to stop, increasing motivation and social support, and minimizing withdrawal symptoms, may be more productive than further emphasis on health risks. Motivating smokers who have not previously tried to stop may involve more emphasis on the health risks of smoking and the health benefits of stopping, as well as on other non-financial benefits of stopping such as social acceptability. Fiscal measures may be particularly effective in motivating this group of smokers to try to stop.