This study aimed to assess whether low doses of albumin in the priming solution for cardiopulmonary bypass (CPB) reduce postoperative bleeding. Three-hundred and seventy-seven patients undergoing CPB were retrospectively assigned to group A (154 patients, CPB primed with 20 ml/kg Ringer Lactate solution + 0.75 mg/kg albumin 20%) and group B (223 patients with 20 ml/kg Ringer Lactate). A significant difference was found in terms of reoperations for bleeding (group A 0/154 versus group B 9/223; P=0.033). The mean number of blood derivatives transfused per patient was higher in group B than in group A (P<0.001). Platelet count after CPB was higher in group A than in group B (175 +/- 52x10(3)/microl versus 131 +/- 70x10(3)/microl; P=0.045). The amount of postoperative bleeding was 525 ml versus 680 ml at 24 hrs (P<0.001), 819 ml versus 1102 ml at 48 hrs, (P<0.001), 963 ml versus 1294 ml at 72 hrs, (P<0.045) (group A versus group B respectively). Crystalloid priming with low-dose albumin reduces postoperative bleeding.