Though the prevalence of cigarette smoking has declined it still remains the leading cause of premature death from chronic disease. In the prevention of tobacco associated disease the promotion of smoking cessation is a key strategy. This article presents a smoking cessation program based on the transtheoretical model, an empirical model distinguishing five stages of behavioral change. Specific interventions are matched to the current stage of change. Smokers in the intervention program repeatedly fill in questionnaires about their smoking habits, attitudes and strategies in the smoking cessation process. The individual questionnaires are analyzed by a computerized expert system which creates letters with comments on the smoking cessation process and suggestions for further steps from a pool of feedback paragraphs. A further component of the program are five stage-matched brochures. The efficacy of the expert system and its potential impact on Public Health are discussed.