Blood pressure fluctuation early in the course of ischemic stroke is a proven independent predictor of morbidity and mortality. Both high and low systolic blood pressures have a detrimental effect on the neurologic outcome. Current guidelines support permissive hypertension in the early course of acute ischemic stroke. For patients with marked elevation in blood pressure, a reasonable goal would be to lower blood pressure by 15% during the first 24 hours after onset of stroke. The level of blood pressure that would mandate such treatment is not known, but consensus exists that medications should be withheld unless the systolic blood pressure is greater than 220 mm Hg or the diastolic blood pressure is greater than 120 mm Hg. For patients undergoing intravenous thrombolysis for acute ischemic stroke, it is recommended that the blood pressure be reduced and maintained below 185 mm Hg systolic for the first 24 hours. The first-line drugs for lowering of blood pressure remain labetalol, nicardi pine, and sodium nitroprusside. These recommendations are based on consensus rather than evidence, however. Comorbid conditions such as myocardial infarction, left ventricular failure, aortic dissection, preeclampsia, or eclampsia would override the guidelines for permissive hypertension; a lower blood pressure would be preferred in these conditions. Children with acute strokes should be managed in the same way as adults, with extrapolated lowering of blood pressures, until further evidence emerges. Current research focuses on both hemodynamic augmentation of low blood pressures and the effects of further lowering the blood pressure after acute ischemic stroke. Until more definitive data are available, a cautious approach to the treatment of arterial hypertension is generally recommended.