Cerebral vasospasm and its associated ischemia are one of the main causes of death in 23% of patients with prior aneurysmal subarachnoidal hemorrhage (SAH). At present, a diversity of approaches to treating vasospasm has been developed, among them hypertensive hypervolemic hemodilution (deriving its abbreviated name 3H-therapy) offers certain advantages. At the same time a number of aspects of application of this approach remain unclear. Fifty-four patients with significant cerebral arterial spasm (elevated linear systolic blood flow velocity > or = 200 cm/s) who had been operated on in the acute period of aneurysmal SAH were selected. Of them, 18 patients had undergone hypervolemic hypertensive hemodilution (3H-therapy) under guidance of systemic hemodynamics, by using a Swan-Ganz catheter (these patients formed a study group). Thirty-six patients who had not undergone 3H-therapy under invasive monitoring of systemic hemodynamics constituted a control group. Hypervolemic hypertensive hemodilution was performed by means of continuous intravenous infusion of a combination of colloid-crystalloid solutions. The therapy was considered to be adequate by meeting the following requirements: maintenance of cardiac index not less 3.5 l/min/m2, pulmonary capillary wedge pressure below 14-16 mm Hg or central venous pressure under to 8-10 mm Hg, packed cell volume below 28-32%, and systolic blood pressure under 200 mm Hg. Hypervolemic hypertensive hemodilution (3H-therapy) applied to patients operated on in the acute period of aneurysmal SAH was effective in increasing cardiac output, central venous pressure, systemic arterial pressure and hence cerebral perfusion with the minimum number of complications unassociated with the use of this technique. This permitted a reduction in mortality rates in patients with baseline Hunt-Hess grade I-III SAH. At the same time, it should be emphasized that 3H-therapy may be used in neurosurgical patients, by thoroughly monitoring the parameters of central hemodynamics, blood coagulation system, cerebral circulation and, desirably, intracranial pressure.