Lowering systemic blood pressure (BP) in patients with acute cerebral infarction may produce clinical deterioration. Because of impaired cerebral autoregulation and the spontaneous fluctuations in BP following stroke, antihypertensive medication should be avoided in patients with acute cerebral infarction unless vital organs such as the heart or kidney are compromised, the diastolic BP rises to 130 mm Hg or greater, or the patient has hypertensive encephalopathy. Brief remarks about BP control in intracerebral hematoma and subarachnoid hemorrhage are also included.