To clarify the efficacy and safety of predeposit autologous blood transfusion (ABT) with concomitant use of recombinant human erythropoietin (rHuEPO) in surgical patients with gastroenterological malignancies, the efficacy was evaluated in terms of observed changes in hemoglobin (Hb) concentration after storage of self-donated autologous blood for elective surgery and the percentage of cases avoiding homologous blood transfusion (HBT). Postoperative changes in values for cellular immunity parameters were compared between the ABT group, HBT group and no transfusion (NT) group.1. The effectiveness rate, as assessed in terms of the decrease in Hb concentration and the preoperative Hb increase, was 67.2%(43/64 cases) for rHuEPO-treated patients of the ABT group after predeposit of 800 ml of autologous blood and 85.7%(6/7 cases) for those of the ABT group after 1, 200ml predeposit. HBT could be avoided in 94.2% of cases (65/69) receiving rHuEPO.2. Of the cellular immune function parameters assessed for postoperative changes, there was a depression of NK activity at weeks 1-2 postoperatively in all three groups. The depression tended to be reversed by week 3 in the ABT and NT groups, whereas the depression was significantly greater and no such recovery was noted in the HBT group. All other parameters showed similar trends of change in the three groups.The results suggest a noticeable usefulness of rHuEPO and that autologous blood transfusion is also useful not only for the prevention of adverse reactions to homologous blood transfusion but also for inhibiting postoperative depression of cellular immune function.