Fifty-five healthy volunteers (thirty young and twenty-five elderly), all of them right-handed, were investigated by Transcranial Doppler monitoring mean flow velocity on the right and left middle cerebral artery at rest, during a motor task performed by the hand and in the following rest condition. In all cases the motor task induced an increase in bilateral mean flow velocity, but significantly greater on the opposite side middle cerebral artery in the task. The percentage increase in mean flow velocity compared to the rest condition observed during the motor task performed by the opposite side hand to the artery investigated was significantly greater in the young than the elderly. Moreover, in the young, this increase showed a slight prevalence during the left middle cerebral artery assessment relating to right hand preference. Furthermore, elderly subjects achieved the greatest mean flow velocity percentage increase compared to rest condition later than young subjects and returned to basal values more slowly.