We examine the bidirectional relationships between cancer risk perceptions and smoking behavior among newly diagnosed cancer patients (N=188) during hospitalization for surgical resection, and at three and 12 months subsequently. Those with higher perceptions of risk for developing another cancer at three months were most likely to abstain from smoking by twelve months. Patients were relatively accurate in their cancer risk perceptions, with relapsers and continuous smokers reporting higher levels of risk perceptions at twelve months. Finally, those who quit smoking by 12 months felt at lower risk for developing cancer by 12 months. None of these relationships were significant between baseline and three months. Results indicate that perceived risk of cancer recurrence may be clinically useful in motivating smoking cessation after the acute cancer treatment phase is over. This study justifies an expanded theoretical framework attending to the distinct, prospective influences of illness risk perceptions on health behavior, and of health behavior on illness risk perceptions.