We report the results of a double-blind, placebo-controlled, multicenter trial on the efficacy of intravenous recombinant tissue plasminogen activator (rt-PA, duteplase) in 98 patients with hyperacute thromboembolic stroke (50% reperfusion in 10 of 47 patients (21.3%) treated with rt-PA and 2 of 46 patients (4.3%) treated with placebo (p = 0.034). The outcome 4 weeks after onset was significantly better in the rt-PA-treated group than in the placebo-treated group, as judged by improvement ratings determined by adjusted percent reduction of the Hemispheric Stroke Scale. Those with successful reperfusion showed significantly better outcome than those without. There were no differences in frequencies of hemorrhagic infarction. The study suggests that early reperfusion of the occluded artery by intravenous rt-PA ameliorates the clinical outcome of hyperacute ischemic stroke patients without increasing the hazard of hemorrhagic complication.