Background It is not clear whether tissue plasminogen activator (t-PA) thrombolysis in patients without major arterial occlusion is effective or safe Methods Consecutive anterior circulation stroke patients treated with t-PA within 3 h of onset were studied The patients were divided into three groups according to magnetic resonance angiography findings before t-PA infusion ICA group, ICA occlusion, MCA group, M1 and M2 occlusion, and no occlusion group Clinical characteristics, the presence of hemorrhagic transformation on T-2* at 24 h after t-PA thrombolysis, and outcome at 3 months were compared among the three groups Results 112 patients were enrolled The no occlusion group had 21 (18 8%) patients, the ICA group had 29 (25 9%), and the MCA group had 62 (55 4%) The frequency of hemorrhagic transformation was only 4 8% in the no occlusion group (31 0% for the ICA group, and 48 4% for the MCA group, p = 0 0012) At 3 months after t-PA therapy, 61 5% of the no occlusion group had a favorable outcome (modified Rankin score 0-1), which was the highest among the three groups (15 0% for the ICA group, and 41 5% for the MCA group, p = 0 0203) Conclusion Intravenous t-PA therapy in acute stroke patients without major artery occlusion seems to be safe and effective Copyright (C) 2010 S Karger AG Basel