20 patients scheduled for total hip replacement were given 1,000 ml of a new preparation of 10% hydroxyethylstarch (HES) (MW 270,000: 0.5) preoperatively. They were compared to a group of 20 patients who received 1,000 ml of 3.5% plasma protein solution (PPS). HES caused a more pronounced hemodilution than PPS. With HES, central venous pressure (CVP) rose significantly higher than with PPS. PTT was significantly prolonged in the HES but not in the PPS group. TT was significantly reduced by HES in comparison to PPS. PT (Quick-value %) and fibrinogen levels showed no difference in both groups. Blood loss and transfusion volume were comparable to HES and PPS until 24 h after the operation. One patient showed generalised flush after HES. This HES preparation is a colloid with volume-expanding properties and appears to be without clinically apparent effects on coagulation (up to a volume of 11).