Colorectal cancers are classically revealed by a low digestive bleeding, which can be occult or exteriorized. They commonly present anemia at the diagnosis leading to particular outcomes. Perioperative blood transfusions are frequently indicated for the treatment of localized tumors and for hepatic resection of metastatic lesions but transfusions seem to have a negative impact on prognosis by increasing infections and potentially recurrence. In this context, various strategies aim at limiting the transfusional risk (autologous transfusion, preoperative use of erythropoietin...). Anemia associated with advanced colorectal cancers provides the same interest as for any metastatic tumor, as quality of life of patients is correlated to the hemoglobin's level.