Background: Vasopressors are used in patients with subarachnoid hemorrhage (SAH) to increase blood pressure with the idea of reversing the ischemic process. The current study is designed to evaluate the changes in systemic and cerebral hemodynamics, including cerebral blood flow autoregulation, at different pharmacologically augmented blood pressure levels using norepinephrine in patients with spontaneous aneurysmal SAH following surgery. Materials and methods: This prospective observational study was carried out in patients with ruptured anterior circulation aneurysms who underwent surgical clipping and required norepinephrine infusion. Postoperatively, when the treating physician decided to start a vasopressor, norepinephrine infusion was started at 0.05 µg/kg/min. The infusion rate was increased by 0.05 µg/kg/min every 5 minutes to achieve a 20% and then 40% increase in the systolic blood pressure (SBP). When the blood pressure stabilized at each level for 5 minutes, hemodynamic and transcranial doppler (TCD) parameters in the middle cerebral artery (MCA) were recorded. Results: Peak systolic, end-diastolic, and mean flow velocities in the MCA increased with targeted blood pressure increase in the hemispheres with impaired autoregulation and not in the hemispheres with intact autoregulation. The interaction of changes in TCD flow velocities between hemispheres with and without intact autoregulation was significant (p < 0.001). Cardiac output changes following norepinephrine infusion were not significant (p = 0.113). Conclusion: Hypertensive therapy with norepinephrine increases cerebral blood flow velocity only when autoregulation is impaired, an effect that is desirable in patients with focal cerebral ischemia following SAH.