Lung carcinoma is one of the most common cancers diagnosed in the USA. A significant portion of these patients have a history of tobacco use and many are smoking at the time of diagnosis. Despite smoking cessation interventions, many patients continue to smoke even after their diagnosis. Those who are able to quit smoking after their diagnosis still have a high rate of relapse of smoking within the first year. Continued smoking has been found to have multiple negative consequences for these patients including increased toxicity from treatment and decreased effectiveness of therapy. Overall, patients who continue to smoke after their diagnosis have poorer outcomes than those patients who are successfully able to quit and abstain from smoking. Knowing this, physicians should encourage smoking cessation in this patient population. Future studies are needed to help define the best approach for encouraging smoking cessation, taking into account patient characteristics and the stress associated with the lung cancer diagnosis.