Smoking after a cancer diagnosis shortens survival time, increases risk of recurrence and the development of another primary tumor, reduces treatment efficacy, and increases treatment complications. Nevertheless, many patients who smoked prior to their illness continue to smoke after diagnosis and treatment. The development of effective smoking cessation interventions for cancer patients has been slowed by the lack of data concerning psychological correlates of smoking in this population. This study, with 74 cancer patients, showed that smoking and lower readiness to quit was associated with: having relatives at home who smoke, a longer time between diagnosis and assessment, completion of medical treatment, greater nicotine dependence, lower self-efficacy, quitting pros, and risk perceptions, and higher quitting cons, fatalistic beliefs, and emotional distress. Thus, smoking cessation treatments for cancer patients should include pharmacotherapy, relapse prevention, and counseling designed to facilitate self-efficacy, quitting pros, and risk awareness and to reduce the quitting cons, fatalism, and distress.