Aim:This study reports mechanical thrombectomy (MT) for internal carotid artery (ICA) occlusion with cross-flow through the communicating artery (“with” group) and compares it to ICA or middle cerebral artery occlusion without cross-flow (“without” group).Material and Methods:This study included 10 and 57 cases of the “with” and “without” groups, respectively. Cases analyzed by rapid processing of perfusion and diffusion (RAPID) since October 2020 were included.Results:Puncture-to-reperfusion time was 78.5 and 39 min (p = 0.0155), the National Institutes of Health Stroke Scale score at discharge was 10.5 and 4 (p = 0.0166), decline from pre to post Diffusion-Weighted Image-Alberta Stroke Program Early CT Score was 0.5 and 0 (p =0.0495), and the modified Rankin Scale score at 90 days was 4 and 2 (p = 0.0195) in the “with” and “without” groups, respectively. Furthermore, Tmax values of >6 s (50 cc vs. 164 cc; p = 0.0277) and Tmax >4 s/Tmax > 6 s ratio (3.23 vs. 1.55) (p = 0.0074) were significantly different between the “with” and “without” groups.Conclusion:The “with” group may have been affected by the longer treatment time and being at high risk of distal migration of thrombus due to poor prognosis. Although the region with a Tmax of >6 s tends to be small in patients of the “with” group, it indicates a low-perfusion state that can lead to cerebral infarction, and MT should be performed.