More recently a number of retrospective analyses in rather ill defined patient populations demonstrated an association between perioperative blood transfusion and recurrence after curative resection of colorectal cancer. In the randomized trial (SAKK 40/81) (adjuvant cytotoxic intraportal infusion versus no further treatment) we evaluated the transfusion status in a well defined, prospectively documented and controlled patient population. Of 457 patients, 353 (77.2%) received either pre-, intra- or postoperatively blood transfusions. After a median follow-up of 4 years, the transfused patients developed significantly more recurrences (38.2%) than patients without blood transfusions (23.1%), the death-rate being 33.7% versus 23.0%, respectively. Patients without transfusion but treated with adjuvant intraportal chemotherapy are strikingly doing better (10.5% recurrences) than patients with perioperative blood transfusion not having an adjuvant treatment (44.5% recurrences).