The study is aimed at getting information the effect of the ex-smoker as an educator on smoking behaviour and the lung vital capacity of the suspect lung cancer patients. The study design is quasi experiment. Respondents of the research are 45 suspect lung cancer patients taken from 4 hospitals. The data are analysed by parametric and nonparametric, level of significant 0.05. The result showed the ex-smoker as an educator able to increase the knowledge score, to decrease the average number of cigarettes smoked per-day and to increasethe vital lung capacity, significantly. Keywords: educator; smoking behaviour; suspect lung cancer patients.