The changes of regional cerebral blood flow (rCBF) related to metabolic demand depend on both integrity of neuronal function and vascular blood flow. Therefore, we assessed the motor stimulus to blood flow velocity (BFv) changes of bilateral middle cerebral arteries (MCA) by transcranial Doppler (TCD) sonography in normal subjects. Eighteen subjects (nine female, aged 48.0+/-3.8 years; nine male, aged 54.4+/-4.8 years) were investigated. Bilateral TCD sonography from both MCA were monitored during ten cycles of 20 s when subjects were performing bilateral hand gripping with a frequency of one per second, and subsequently 20 s when they were rest. Bilateral hand gripping showed a significant BFv increase on both MCA (P<0.001). These values were (19+/-2)% on both sides. There was no significant side to side difference between the absolute BFv values both at rest and during bilateral hand gripping. Additionally, the absolute BFvs and BFv increases were not significantly different between male and female subjects. This study was based on a small sample size, and the method requires the subject cooperation. Our results suggest that bilateral hand gripping may affect blood flow in both MCA without side to side differences. Finally, our suggestion is that test might be useful to assess the neurovascular integrity.