This prospective, randomized controlled study evaluated the effects of acute hypervolaemic haemodilution (AHH) on the expression of plasma interferon-inducible protein-10 (IP-10) and bactericidal/permeability-increasing protein (BPI) in patients undergoing elective total hip replacement. Twenty patients were randomized to receive an infusion of either hydroxyethyl starch (HES group) or lactated Ringer's solution (LR group) immediately after anaesthesia. Plasma concentrations of IP-10 and BPI were measured before anaesthesia (baseline), at the start of surgery, 30 min after the start of surgery and at the end of surgery. Blood loss and the volume of blood transfused were significantly lower in the HES group compared with the LR group. Compared with baseline, IP-10 and BPI concentrations increased significantly in both groups 30 min after the start of surgery. The IP-10 concentrations were significantly lower and BPI concentrations significantly higher in the HES group compared with the LR group 30 min after the start of surgery and at the end of surgery. It is concluded that AHH with HES may be helpful in ameliorating immune function during total hip replacement and in reducing blood loss and the extent of blood transfusion.