Abstract: Aim The change of the blood apparent viscosity following traumatic brain injury and the effect of iloprost on it were observed.Methods The mode rate brain trauma of rabbits was produced with the PBI-Ⅱ type injury device.The brain trauma was treated with iloprost (30 μg·kg^-1, iv).The blood samples at 1、6 and 24 h following brain trauma were collected.The apparent viscosity was measured with The Low Shear 30, and the hematocrit was measured meanwhile.The coefficient of the power function and the calculative apparent viscosity at the time when the hematocrit was 0.40, were compared.Results The blood viscosity was significantly increased at 1 h after brain trauma, and was increased continually at 6 h, but at 24 h it was distincly decresed as compared with that at 6 h.It was more increased after brain trauma at low shear than that in the control group.The blood viscosity both in the trauma and control groups was markedly decreased by the effects of iloprost. Conclusion The changes of the blood viscosity after brain trauma may play a role in the occurrence of the secondary brain damage.iloprost may be an effective drug for treating traumatic brain injury.

Key words: traumatic brain injury, apparent viscosity, iloprost