This study is designed to clarify the benefits and risks of chemotherapy and radiation therapy in elderly patients with colorectal cancer through a systematic review of the literature. Searches of the Medline, Embase, and Cochrane Library databases; PDQ Cancer Information Summaries, American Society of Clinical Oncology Guidelines, Cancer Care Ontario Practice Guideline Initiative, Interprovincial Drug Strategies and Guidelines Group, and OncoLink Web sites; and manual searches of meeting proceedings and bibliographies were performed. Additional studies known to the authors were also identified. Randomized controlled trials, reviews, and guidelines evaluating the impact of age on overall survival and/or toxicity with adjuvant and palliative therapies for colorectal adenocarcinoma were selected. A preset study selection form was applied to all identified studies. All selected studies underwent a preset study appraisal. Analyses of the effect of age on overall survival benefits and/or toxicity of therapy were extracted. A qualitative synthesis and narrative review was undertaken. There is good evidence to support that patients = 80 years of age have similar overall survival benefits with adjuvant 5-fluorouracil (5-FU)-based chemotherapy for colon cancer and with palliative first-line monotherapy for metastatic colorectal cancer, as do younger patients. Data are limited with regard to toxicity of therapy in older patients in these settings. An increase in toxicity with bolus 5-FU chemotherapy regimens is evident. There is a paucity of data regarding adjuvant treatment of older patients with rectal cancer. More elderly patients need to be enrolled in clinical trials in order to fully evaluate the outcomes of colorectal cancer therapy in this population. Further studies are warranted.