To evaluate the cerebral blood flow velocity in patients with ocular hypertension.Twenty-four ocular hypertensive patients and 24 age- and sex-matched healthy volunteers were recruited in a prospective comparative study. All subjects had normal findings on full-threshold visual field tests and clinically normal optic nerves. All patients with ocular hypertension had an intraocular pressure (IOP) of >21 mmHg on three separate occasions without treatment. Systolic and diastolic blood pressure by cuff, heart rate by palpation, IOP by Goldmann applanation tonometry, central corneal thickness by ultrasound pachymetry, blood flow velocities, and pulsatility index of the ipsilateral middle cerebral artery by transcranial color Doppler were measured.Systolic and diastolic blood pressures (P=0.40 and P=0.45, respectively), heart rate (P=0.30), and central corneal thickness (P=0.23) were similar in each group. Peak and end-diastolic blood flow velocities in the middle cerebral artery did not differ between ocular hypertensives and controls (P=0.37 and P=0.87, respectively). In addition, pulsatility index did not significantly differ between ocular hypertensives and controls (P=0.61).The results of this study suggest that ocular hypertension is not associated with reduction in blood flow velocity and elevation of resistance in the middle cerebral artery.