Objective To evaluate the effect of auto-blood transfusion on immune function in patients underwent total hip replacement. Methods 50 patients underwent total hip replacement (THR were randomly divided into two groups: A group (auto-blood transfusion, n=25) and B group (variant-blood group, n=25). The auto-blood or variant-blood was transfused depends on intraoperative bleeding . Levels of CD4+, CD8+, NK, IL-2 and IL-6 in the plasma was assessed before anesthetizing, 2 days and 5 days after blood transfusion by flow cytometry. Results Compared to the preoperative levels of CD4 +, CD8 +, NK cells and IL-2 [（40±8）, (28±9), (9±4)%, (839±472）ng/L], their levels in group B decreased at days 2 [（35±6）,（22±6）,（7±3）%,（523±407）ng/L] and 5 [（35±6）, (26±8), (6±4)%, (442±376）ng/L] after blood transfusion (P <0.05).The levels of CD4 + and CD8 +[(39±8),（27±9）ng/L] at days 5 after blood transfusion was not different compared to their preoperative levels, and there was no difference in levels of NK cells and IL-2 at days 2 [(8±4)%,（807±534）ng/L] and 5 [(8±4)%,（821±437）ng/L] after blood transfusion compared to their preoperative levels in group A. The levels of IL-6 at days 2 [(3 198±698) ng/L] and 5 [(3 076±703) ng/L] increased compared with their preoperative level [(2 593±784) ng/L] in group A(P<0.05). Conclusions Auto-blood transfusion is a safe and reliable blood protective method which had no obviously depressive effect on immune function in patients underging total hip replacement operation..