Stroke is a common and disabling condition. Intravenous tissue plasminogen activator (tPA) administered within 3 h of symptom onset is the standard therapy for eligible patients with acute ischemic stroke. Unfortunately, because of the time limitation, very few patients with ischemic stroke actually receive this treatment. In order to increase the number of patients who may benefit from acute treatment, recent research has focused on expanding the time window for thrombolysis and improving its efficacy to ultimately improve patient outcome.