Colorectal cancer is the fourth most common noncutaneous malignancy in the United States and the second most frequent cause of cancer-related death. Approximately three quarters of patients are diagnosed with disease limited to the bowel wall or surrounding lymph nodes. Over the past decade, significant progress has been made in the treatment of localized colorectal cancer due to advances in surgery, radiotherapy, and chemotherapy. For patients with Stage III colon cancer, an overall survival benefit for fluorouracil-based chemotherapy has been firmly established, and recent data have shown further efficacy through the inclusion of oxaliplatin into adjuvant treatment programs. For patients with Stage II colon cancer, the use of adjuvant chemotherapy remains controversial, but may be appropriate in a subset of individuals at high risk for disease recurrence. In the treatment of patients with rectal cancer, improved outcomes have been noted with the use of total mesorectal excision and preoperative concurrent chemoradiotherapy. Current randomized clinical trials in the adjuvant therapy of colorectal cancer are examining the value of adding agents known to be active in metastatic disease, including those that modify specific molecular targets.