The paper provides the results of a complex experimental and clinical study of the effects of infusion solutions of hydroxyethyl starch (HES 200/0.5--Refortan and HES 130/0.4--Voluven) on hemostatic and systemic hemodynamic parameters in patients operated on for neurosurgical pathology of the brain. The HES solutions are shown to have a more pronounced volemic effect and a slightly higher hypocoagulation effect on the hemostatic system (as compared with physiological solution); the latter does not, however, achieve its clinical value with the used doses of the solutions.