Intravenous administration of tissue plasminogen activator (t-PA) can improve clinical outcome in patients with acute ischemic stroke. In our country, use of t-PA for acute brain infarction within 3 hours of onset was approved by Japanese government from October, 2005. About 5,700 patients were treated with t-PA for these two years. Analysis of 2,484 patients (mean 70 years old, median NIHSS Score 15) showed that mRS 0-1 was 32%, the death was 20% and symptomatic brain hemorrhage was 5.2%. We had 63 patients (median 74 years old, median NIHSS score 14) treated with t-PA thrombolysis by November, 2007. Immediately after t-PA therapy 8 patients (12.7%) had dramatic recovery. On day 7 after t-PA therapy, excellent recovery was 49.2%, good recovery was 15.9%, and worsening was 12.7%. Within one hour after t-PA therapy, rate of recanalization for occluded arteries was 43.5%, which was strongly associated with excellent and good neurological recovery on day 7. Atrial fibrillation was an independent factor associated with no early recanalization. When we evaluated baseline DWI findings before t-PA infusion using DWI-ASPECTS and NIHSS score at day 7 after rt-PA therapy, bad outcome was seen more frequently in patients with an DWI ASPECTS < or = 5 (6 of 8 patients) than in patients with an DWI ASPECTS > 5 (2 of 41 patients; P < 0.0001). Patients with an ASPECTS-DWI > 5 should be considered eligible for t-PA therapy.