Acute ischemic stroke is a common, devastating disorder without beneficial therapy. Recent advances concerning the pathophysiology of ischemic brain injury have led to the development of rational pharmacological interventions. Thrombolytic and cytoprotective therapies may be useful and are being evaluated in clinical trials. The design of adequate clinical trials to evaluate these promising therapies has also evolved based on experience. Potential therapy for acute ischemic stroke must be assessed in a large number of patients who are given the intervention within hours of onset using a neurological scoring scale and a disability scale. Several new magnetic resonance imaging technologies are emerging that should allow the clinician to rapidly and accurately identify ischemic brain lesions and to evaluate cerebral perfusion. The availability of potentially efficacious therapies for ischemic stroke evaluated in well-designed clinical trials with magnetic resonance imaging technology, which can also assess therapeutic effects in vivo, should lead to the emergence of therapy to improve the outcome of patients with ischemic stroke in the near future.