Objective: We evaluated the impact of demographic factors, smoking patterns, and the occurrence of smoking-related diseases on smoking cessation, with a particular emphasis on the temporal relationship between diagnosis of smoking-related diseases and cessation. Study Design and Setting: A cohort was assembled of participants of a general health screening examination aged 50-74 years. Lifetime smoking habits and medical history were obtained by a self-administered questionnaire. In a retrospective cohort study approach, predictors of cessation among ever-smokers (n = 4,575) were identified using the extended proportional hazards model. Results: Male gender, late onset of smoking, and higher educational level were predictive of cessation. However, the by far strongest predictors of cessation were diagnoses of smoking-related diseases: relative cessation rates in the year of disease occurrence were 11.2 for myocardial infarction (95% confidence interval CI = 8.9-14.0), 7.2 for stroke (95% CI = 5.1-11.6), 2.5 for diabetes mellitus (95% CI 1.6-4.0) and 4.8 for cancer (95% CI = 3.1-7.4) relative to years before diagnosis of the respective diseases. Conclusion: Our results underline the key role of perceived detrimental effects of smoking for cessation. When smokers personally experience the health consequences of smoking, many permanently quit. (c) 2006 Elsevier Inc. All rights reserved.