Background: The purpose of this study was to clarify the clinical impact of endovascular treatment (EVT) on acute cerebral large vessel occlusion using a nationwide survey of Japan conducted in 2009. Methods: Patients admitted within 24 h after stroke onset were registered retrospectively. Treatment selection, methods, and clinical results were analyzed. Results: A total of 1,963 patients (855 women, 1,108 men) treated in 2008 were registered from 68 medical centers in Japan. Mean age on admission was 74.1 ± 12.2 years (range 7–100 years). The first treatment was conservative therapy in 68%, intravenous tissue plasminogen activator (IV-tPA) in 21%, EVT in 9%, and combined IV-tPA + EVT in 2%. EVT mainly comprised angioplasty, intra-arterial thrombolysis and/or the combination of both. Patients treated ≤3 h after onset (1,286 cases) showed better clinical outcomes with combined IV-tPA + EVT than with conservative therapy, and significant differences in outcomes were seen for patients with occlusion of the basilar artery (p < 0.01) or middle cerebral artery (p < 0.01), but not the internal carotid artery. At >3 h after onset (677 patients), no IV-tPA was performed, and EVT was performed in 11%. Among the patients treated by EVT, there were significant differences in clinical outcome between complete recanalization (TIMI grade 3) and partial/no recanalization (TIMI grade 0–2) (p < 0.001; OR 5.98; 95% CI 3.27–10.96) and between any recanalization (TIMI grade 1–3) and no recanalization (TIMI grade 0) (p < 0.001; OR 36.15; 95% CI 4.88–267.53). Conclusions: This nationwide survey showed the efficacy of EVT with IV-tPA in patients with occlusion of the basilar or middle cerebral artery, but not of the internal carotid artery. The effects of new endovascular devices should be clarified in the near future.