In the last few years, an enormous progress has been achieved in the treatment of Colorectal Cancer due to a better know ledge of the biology, natural history, prevention and treatment of colon and rectum adenocarcinoma. Genetic alterations produce changes in thecolonic mucosa that lead to the formation of adenoma and eventually, its transformation into cancer. At present, it is well established that the Adenomatous Polyp preceeds Colorectal Cancer. The average span of time from normal mucosa to Adenomatous Polyp is about 5 years, and it takes around 5 more years for the Adenomatous Polyp to transform into cancer. The treatment of patients with Colorectal Cancer varies from Endoscopic Polypectomy or formal surgical resection to combined multidisciplinary strategies, according with the stage of the disease. Endoscopic Polypectomy has helped to avoid multiple operations that were performed in the past, it also reduces significantly the development of a second cancer in cured patients who had suffered Colon Cancer. The prognosis of node-negative patients is excellent with a 5 year survival of 80 per cent. Adjuvant chemotherapy has proven to be effective in node-positive Colon Cancer, improving the overall survival. In Rectum Cancer, the use of staplers and changes in the surgical technique have reduced the number of abdominoperineal resections, preserving the annal sphincter and improving the quality of life in patients. Adjuvant chemoradiation control groups and historical controls show a local recurrence of 20-45 per cent in node-positive Rectum Cancer, and 15-30 per cent in node-negative patients. Recently, the improvement of the lateral dissection reduces recurrence in 10 per cent, avoiding pelvic pain, although overall survival has not been improved. Local excision of early lesions from the rectum is an interesting choice in patients who have been carefully selected. We believe that in the following years, the clinical appearance of Colorectal Cancer can be prevented with a better knowledge of its molecular biology.