12g/dl. The patients were premedicated with intramuscular atropine 0.01 mg ? kg-1 and midazolam 0.06 mg?kg-1 . Anesthesia was induced with fentanyl 3-5?g?kg-1, propofol 1.5-2.0 mg?kg-1 and vecuronium 0.1 mg ? kg-1 and maintained with inhalation of 60%-65% N2O-O2 and 1%-3% isoflurane. The patients were mechanically ventilated after tracheal intubation and PETCO2 was maintained at 4.67-5.33 kPa. Radial artery was cannulated for intra-arterial pressure monitoring and blood sampling and internal jugular or subclavian vein was cannulated for CVP monitoring and blood sampling. Before anesthesia 5% glucose-normal saline 6-8 ml?kg-1 was infused to compensate for preoperative fluid restriction after midnight. 6% HES 200/0.5 15 ml?kg-1 was infused before operation in 25 min. The inhalation concentration of isoflurane was adjusted to maintain CVP, BP and HR and avoid circulatory overload. Small dose of nitroglycerin (NTG) was given iv if necessary. During operation blood loss was replaced with equal volume of 6 % HES 200/0.5. Blood transfusion was considered when Hb 25% . Diureties was used at the end of surgery. ECG, BP, CVP, SaO2 and cardiac output (using non-invasive NCCOM-3) were continuously monitored throughout operation. Arterial and centralvenous blood samples were taken for blood gas analysis and determination of lactic acid concentration (LA) before (T0) and 15 min (T1) after AHHD, before homologous blood transfusion (T2 ) and at the end of surgery (T3) . Oxygen consumption (VO2 ) and oxygen extraction ratio (ERO2) were calculated. Results (1) There were no significant changes in BP and HR after AHHD and during operation. CVP increased significantly after AHHD at T1-3 but within normal range. Cardiac output increased by 22.9% (T1), 17.0% (T2) and 30.5% (T3) after AHHD. (2)Hct and Hb decreased gradually after AHHD as hemodilution continued and five patients received homologous RBC transfusion because of low Hb. DO2 increased by 11% after AHHD. In five patients DO2 and VO2 prior to homologous RBC transfusion were lower than baseline value (T0). ERO2 increased by 13.5% (T1), 34.9% (T2) and 24.9% (T3) respectively. (3) Electrolytes, pH and LA were kept stable throughout operation. Conclusions 6% HES 200/0.5 can be used safely for AHHD in terms of hemodynamic changes and oxygen transport and ERO2.