The optimal management of arterial blood pressure in the setting of an acute stroke has not been defined. Many articles have been published on this topic in the past few years, but definitive evidence from clinical trials continues to be lacking. This situation is complicated further because stroke is a heterogeneous disease. The best management of arterial blood pressure may differ, depending on the type of stroke (ischemic or hemorrhagic) and the subtype of ischemic or hemorrhagic stroke. This article reviews the relationship between arterial blood pressure and the pathophysiology specific to ischemic stroke, primary intracerebral hemorrhage, and aneurysmal subarachnoid hemorrhage, elaborating on the concept of ischemic penumbra and the role of cerebral autoregulation. The article also examines the impact of blood pressure and its management on outcome. Finally, an agenda for research in this field is outlined.