Background and purpose: Recent study reported the impact of complete recanalization beyond significant recanalization. The main of present study is to investigate the impact of complete recanalization in stroke patients with distal (M2) middle cerebral artery (MCA) occlusion. Methods: From our prospective endovascular thrombectomy (EVT) registry and multicenter tPA trial (YAMATO study) data bank, data on M2 occlusion and treated with EVT and/or tPA were retrospectively reviewed. In the YAMATO study, all tPA patients were examined using MRA before and at 1 hour after tPA. Thus, we defined the complete recanalization as a modified TICI of 3 at the end of EVT or similar appearances of both MCA on MRA at 1 hour after tPA. Significant recanalization was TICI ≥2b or >50% recanalization of MRA. At 3 months, favorable outcome was defined as mRS ≤ 2. Result: Data on 122 patients with M2 occlusion (median age 79 [72-85] years; male, 69 [57%], NIHSS score 13 [8-19]) received tPA and/or EVT were analyzed. Onset-to-admission was calculated as 95 (52-189) minutes. Complete recanalization was achieved in 27 (22%) patients, and significant recanalization was in 75 (61%) patients. Neither EVT administration it self, tPA, combined EVT and tPA were related to the complete recanalization (p=0.383, 0,237 and 0.612). At 3 months onset, patients with complete recanalization at the end of EVT/tPA frequently had favorable outcome than those without it (75% vs. 43%, p=0.013), while significant recanalization did not statistically increase the rate of favorable outcome (52% vs. 46%, p=0.673). Age, NIHSS score, DWI-ASPECTS, and plasma levels of d-dimer and brain benign peptide were also related to the favorable outcome (0.031, <0.001, 0.005, 0.011, and 0.010). Finally, multivariate regression analysis found that complete recanalization was an independent parameter related to the favorable outcome (odd ratio, 5.0 95%CI [1.1-23.0], p=0.038) as well as DWI-ASPECTS (odds ratio, 2.1, 95%CI [1.2-3.3], p=0.001). Conclusion: Complete recanalization but not significant recanalization was a parameter associated with favorable outcome in M2 occlusion patients. The goal of recanalization therapy may be immediate and complete recanalization even in patients with distal MCA occlusion.