This study tested the hypothesis that colloidal blood volume expansion could improve the cerebral circulation during high intracranial pressure. We studied cerebrovascular haemodynamic variables during high intracranial pressure with and without colloidal blood volume expansion in 12 pigs, whereas five pigs served as controls with intracranial pressure increase twice without colloidal blood volume expansion. Cerebral blood flow was measured with ultrasonic flowmetry on the internal carotid artery, and cerebral microcirculation with laser Doppler flowmetry. High intracranial pressure was induced by infusion of artificial cerebrospinal fluid into the cisterna magna. Blood volume expansion was obtained by infusion of albumin, 1 gram/kg. Albumin infusion caused increases in internal carotid artery blood flow (P < 0.05) and cerebral perfusion pressure (P < 0.005), while cerebral microcirculation and cerebrovascular resistance was unchanged. High intracranial pressure albumin infusion caused internal carotid artery blood flow (P < 0.05) and cerebral perfusion pressure (P < 0.001) to increase compared to high intracranial pressure without albumin infusion, while cerebrovascular resistance was unchanged. Cerebral micro-circulation tended to increase, but this was not statistically significant (P = 0.07). Augmentation of the intravascular blood volume during high intracranial pressure increased the arterial inflow to the brain and possibly the cerebral microcirculation by increasing the cerebral perfusion pressure. Our results tend to support that the effect of colloidal blood volume expansion is beneficial for the cerebral circulation during high intracranial pressure.