Conventional wisdom has held that it is necessary to start intravenous thrombolytic treatment for acute ischemic stroke within 4.5 hours of the onset of symptoms. Results of a multicentre, randomized, placebo-controlled trial recently published in the New England Journal of Medicine suggest that a rethink might be warranted. Patients who had an ischemic stroke and who had hypo-perfused but salvageable regions of brain detected on automated perfusion imaging were randomly assigned to receive intravenous alteplase or placebo between 4.5 and 9.0 hours after the onset of stroke or upon awakening with stroke (if within 9 hours from the midpoint of sleep). 113 patients were assigned to the alteplase group and 112 got placebo. The primary outcome was a Rankin Score consistent with so symptoms at all OR no significant disability despite symptoms (able to carry out all usual duties and activities) and was found to have been achieved for 40 patients (35.4%) in the alteplase group and in 33 patients (29.5%) in the placebo group (adjusted risk ratio, 1.44; 95% confidence interval [CI], 1.01 to 2.06; P=0.04). Symptomatic intracerebral hemorrhage occurred in 7 patients (6.2%) in the alteplase group and in 1 patient (0.9%) in the placebo group (adjusted risk ratio, 7.22; 95% CI, 0.97 to 53.5; P=0.05). The administration of alteplase between 4.5 and 9.0 hours after stroke onset or at the time the patient awoke with stroke symptoms resulted in a higher percentage of patients with no or minor neurologic deficits than the use of placebo, but there were symptomatic cerebral haemorrhages in the alteplase group than in the placebo group.