While the benefits of exercise for managing cancer-and treatment-related side effects has been shown among various populations of cancer survivors, a relative dearth of information exists among older cancer patients. OBJECTIVES: To determine the prevalence of exercise participation during and after primary cancer treatment in older (≥65 years) and the oldest (≥80 years) cancer patients and to examine the relationships between exercise, symptoms, and self-rated health (SRH). MATERIALS AND METHODS: 408 newly diagnosed older cancer patients (mean age=73, range=65-92) scheduled to receive chemotherapy and/or radiation therapy reported symptoms and SRH prior to, during, and 6 months after treatment, and exercise participation during and following treatment. RESULTS: Forty-six percent of older and 41% of the oldest patients reported exercising during treatment. Sixty percent of older and 68% of the oldest patients reported exercising in the 6 months thereafter. Older patients who exercised during treatment reported less shortness of breath and better SRH during treatment, and better SRH following treatment. The oldest patients who exercised during treatment reported less memory loss and better SRH during treatment and less fatigue and better SRH following treatment. The oldest patients who exercised following treatment reported less fatigue, skin problems, and total symptom burden following treatment. CONCLUSION: These data suggest a willingness of older cancer patients to attempt exercise during and after treatment. Exercise during these times is associated with less severe symptoms; further clinical research examining the efficacy of formal exercise interventions to reduce symptoms and improve SRH in older cancer patients is needed.