Clinical data from Japan on the safety and real-world outcomes of alteplase (tPA) thrombolysis in the extended therapeutic window are lacking. The aim of this study was to assess the safety and real-world outcomes of tPA administered within 3–4.5 h of stroke onset. The study comprised consecutive acute ischemic stroke patients (n = 177) admitted across five hospitals between September 2012 and August 2014. Patients received intravenous tPA within <3 or 3–4.5 h of stroke onset. Endovascular therapy was used for tPA-refractory patients. In the 3–4.5 h subgroup (31.6 % of patients), tPA was started 85 min later than the <3 h group (220 vs. 135 min, respectively). However, outcome measures were not significantly different between the <3 and 3–4.5 h subgroups for recanalization rate (67.8 vs. 57.1 %), symptomatic intracerebral hemorrhage (2.5 vs. 3.6 %), modified Rankin Scale score of 0–1 at 3 months (36.0 vs. 23.4 %), and mortality (6.9 vs. 8.3 %). We present data from 2005 to 2012 using a therapeutic window <3 h showing comparable results. tPA following endovascular therapy with recanalization might be superior to tPA only with recanalization (81.0 vs. 59.1 %). Compared with administration within 3 h of ischemic stroke onset, tPA administration within 3–4.5 h of ischemic stroke onset in real-world stroke emergency settings at multiple sites in Japan is as safe and has the same outcomes.