Background. In a population-based sample of smokers in early motivational stages, we found a high acceptance of smoking cessation groups. Methods. Inter99 is a randomized population-based intervention study, in Copenhagen, Denmark. Smokers in all motivational stages were included. All participants underwent a lifestyle consultation and 2,168 smokers in the high intensity intervention group were offered assistance to quit in smoking cessation groups. Results. Thirty-five percent were validated to be continuously abstinent at the end of the smoking cessation groups. Eighty-four percent of the smokers achieving sustained abstinence in our study had no serious plans to quit soon before the lifestyle consultation. Motivation to quit before the lifestyle consultation could not predict abstinence. Being a man, and having a job and at least 1 year of vocational training were predictors of abstinence in a multivariate model, whereas high nicotine dependence and living with a smoking spouse were predictors of failure. Conclusion. High cessation rates were obtained in a population of heavy smokers with moderate nicotine dependence. It was possible to obtain sustained abstinence in smokers in early motivational stages. These smokers would probably not have been reached by traditional smoking campaigns.