Smoking cessation improves response to chemotherapy and targeted therapy which can decrease lung cancer so, this study aimed at evaluating the effectiveness of smoking cessation program on lung cancer patients. Setting: The study was conducted in the outpatient clinic of the oncology center, affiliated to Ain Shams University Hospitals. Subjects: The study was conducted on 60 patients. Tools of data collection were; 1) Socio-demographic sheet to assess age, sex, residence, monthly income….etc, smoking history, quitting history& patients' knowledge. 2) Fagerstrom Test For Nicotine Dependence. 3) Computed assisted tomography scan (CT scan) of the chest. 4) The piCO Smokerlyser (Bedfont Scientific, Harrietsham, England), a portable carbon monoxide (CO) monitor. The result showed that, there was a highly statistically significant difference between pre-and post-intervention of smoking intensity, total knowledge scores of the patients and CT scan findings to evaluate lesion response (p=≤0.001). In addition, there were highly statistically significant differences between pre-and post-intervention of the performance status of the patients and their perceived health (p=≤0.001). Moreover, there were highly statistically significant differences between pre-and post-intervention of methods of quitting and supporting system for the patients (p=≤0.001). It was concluded that, the implementation of the smoking cessation program had a positive effect on the lung cancer smokers' patients. The study highlighted the recommendation of incorporating smoking cessation intervention into nursing curriculum at all levels of nursing education and in oncology centers, it should focus not only on the risks of continued tobacco use, but also and mainly, on supporting long-term abstinence and reducing relapse risk factors, which are very common in these patients.