The hemodynamic effects of 6% hydroxyethyl starch (HES) 200,000/0.62 were investigated in 20 patients (7 female, 13 male) who required invasive (Swan-Ganz/radial artery catheter) monitoring during major surgery. In 8 patients infrarenal aneurysmectomy and implantation of a bifurcation prosthesis was carried out, in 10 patients with arteriosclerotic vessel disease a bifurcation prosthesis was implanted, in 1 patient a renal artery aneurysm was repaired, and in another abdominosacral rectum amputation was performed. After induction of general anesthesia with alcuronium 2 mg, fentanyl 0.25-0.5 mg, droperidol 2.5-7.5 mg, thiopental 250-375 mg, succinylcholine 100 mg, and alcuronium 8 mg, the patients were ventilated with an O2-N2O ratio of 1.4:3 and halothane 0.4-0.6 vol%; the left radial artery was cannulated and a Swan-Ganz catheter was introduced percutaneously via the right internal jugular vein. According to clinical needs, repetitive doses of alcuronium, droperidol, and fentanyl were administered. At pulmonary capillary wedge pressures (PCWP) of 8-10 mm Hg arterial and mixed-venous samples were drawn for blood gas analysis and saturations; arterial blood pressure (systolic, diastolic), pulmonary artery pressure (systolic and diastolic), and central venous pressure were measured. Five measurements of cardiac output were carried out with cold saline solution, the highest and lowest values discarded, and the hemodynamic variables calculated based on the average of the remaining three values. All hemodynamic data were measured with the Siemens SIRECUST 400/404 monitoring system. Measurement of injectate temperature was done by on-line thermistor GOULD SP 5045. (ABSTRACT TRUNCATED AT 250 WORDS)