Report of a retrospective study on 303 patients operated from colorrectal carcinoma to whom colonic resection was done in B and C stages of Astler-Coller's clasification. The aim was to try to find a relation between blood transfusion and colorrectal carcinoma recurrence. The statistical study is made with the program LOGIT(R) , studying the surgical incision, evolutive stage and blood transfusion variables. The significant contribution of each variable in the ocurrence of recurrence is studied with the Wald Test. As a result it can be deduced that the prognossis of colorrectal cancer is influenced by three factors: the evolutive stage, the surgical incision (1.87 times more frequent for the abdomino-perineal) and the transfusion of more of three units of blood in the perioperative period which multiplies by 2.85 the risk of recurrence of colorrectal carcinoma. In our Hospital almost exclusively red cell concentrates (including red cells, white cells and minimal fraction of plasma), are transfusioned; possibly the white cells are responsible for the recurrence.