In the National Institutes of Health rt-PA Stroke Study, treatment of ischemic stroke within 3 hours of onset with intravenous tissue plasminogen activator resulted in improved neurologic outcome, without increased mortality from intracerebral hemorrhage. Experimental neuroprotective therapies may soon provide the opportunity to further limit ischemic damage, either alone or in combination with thrombolysis. New imaging techniques, such as diffusion-weighted magnetic resonance imaging, have been shown to detect acute ischemia before infarction develops and may eventually revolutionize the diagnosis of acute stroke. At the present time, however, ICU care for victims of severe stroke remains primarily supportive, and survivors are often left with profound neurologic deficits. Outcomes research is required to determine which patients are most likely to benefit from heroic supportive care for lifethreatening stroke.