BACKGREOUND: Cerebral damage caused by hemorrhagic shock presents an important challenge for critical care medicine. The type of fluid to resuscitate hemorrhagic shock is important for the outcome of such patients. Pentastarch is low-molecular-weight hydroxyethyl starch, which increases cerebral blood flow (CBF) by plasma volume expansion and compensatory vasodilation, and improves the microcirculation in the ischemic brain area by reducing the blood viscosity. METHODS: The authors continuously determined CBF and CMRO2 in 10 mongrel dogs weighing 20.1 +/- 0.8 kg with posterior sagittal sinus outflow method. Dogs were subjected to the 20 minute-period of hemorrhagic shock to a mean arterial pressure of 40 mmHg. The shock phase was followed by resuscitation with the same volume of 10% pentastarch as blood loss. The authors assessed the changes of CBF, CMRO2, and CBF/CMRO2 ratio immediately and 30, 60, 90, 120 minutes after pentastarch infusion. Brain water content was assessed by the wet-dry weight method. RESULTS: CBF was increased above the control level, immediately and 30 minutes after 10% pentastarch infusion (p<0.05), and approximated to the control level for the remaining time. CMRO2 was increased, immediately and 30, 60, 90 minutes after 10% pentastarch infusion (p<0.05), and approximated to the control level at 120 minutes. CBF/CMRO2 ratio was recovered to the control level after 10% pentastarch infusion. Brain water content was not significantly different from the normal value of dogs. CONCLUSION: 10% pentastarch may be used with safety to resuscitate hemorrhagic shock because it recovers the balance between the cerebral oxygen supply and demand, and does not cause cerebral edema.