Background: Colorectal cancer (CRC) diagnosis and treatment can have substantial detrimental impacts on health related quality of life (HRQOL) and physical function. This is especially true for older CRC patients and is of paramount concern in chemotherapy treatment decision making; yet, few studies to date have focused on understanding and managing fatigue in older CRC patients. We present the design of a study to evaluate the feasibility and impact of a home-based, self-directed physical activity intervention on fatigue in older CRC patients receiving adjuvant chemotherapy treatment. Secondary aims pertain to intervention impact on HRQOL, physical function, and self-efficacy for managing fatigue. Methods/design: Multi-site, randomized controlled trial of physical activity intervention compared to usual care in a sample of older adults undergoing adjuvant chemotherapy for CRC. Forty CRC patients will be recruited and study questionnaires/assessments will be performed at baseline, 3months, and after completion of adjuvant chemotherapy. The primary outcome is a comparison of the change in fatigue from baseline to 3months between Intervention and Control arms. We will also compare changes in engagement in physical activity, HRQOL, physical function, and self-efficacy. Exploratory analyses will compare Intervention and Control arms with regard to changes in muscle mass and a biomarker aging that is known to increase during chemotherapy (p16INK4a). Discussion: If positive, findings from this pilot study would suggest the potential for improving the care of older persons with CRC undergoing adjuvant chemotherapy through a home-based physical activity intervention to manage fatigue, HRQOL, and physical function.Trial Registration: NCT02191969.