Objective To observe the expression of heat shock protein 70 (HSP70) in human liver after hepatic transplantation, and to study its correlation with the occurrence and progression of acute allograft rejection.Methods Fifteen biopsy specimen of allograft liver after transplantation were collected and divided into three groups according to their pathological changes: control group (no rejection), mild acute rejection group, and moderate/serious acute rejection group. The expressions of HSP70 in grafts were detected by using immunohistochemical method and imaging analysis. Results HSP70 was expressed in all 3 groups, and appeared mainly in hepatocellular cytoplasm. The immunohistochemical imaging analysis of HSP70 showed: integral optical density (IOD) which was 30.99±11.14 in the control group was lower than that in the mild acute rejection group (68.84±21.37) and that in the moderate/serious acute rejection group (71.82±19.99), P＜0.01； and the IOD in the moderate/serious acute rejection group was higher than that in the mild acute rejection group (P＜0.05). Conclusion HSP70 plays a role in cellular protection for allograft liver, and the continuously increasing expression of HSP70 in graft maybe closely relates to the occurrence and progression of acute allograft rejection.