Parenchymal hematoma (PH) worsens the prognosis in acute ischemic stroke patients who undergo endovascular thrombectomy (EVT). Dynamic cerebral autoregulation (dCA), the brain's ability to maintain stable cerebral blood flow despite fluctuating blood pressure, may be impaired in these patients. However, the relationship between PH and dCA remains unclear. The aim of this study was to investigate the correlation between PH after EVT and impaired dCA.We recruited patients who suffered from anterior large-vessel occlusion and underwent EVT. The dCA parameters, including gain, phase, and coherence, were measured 24 hours and 2-3 days post-EVT. The change in phase between these time points was calculated (Δphase = phase2-3 d - phase24 h). The European Cooperative Acute Stroke Study II guidelines were used to evaluate PH. Clinical outcomes were measured by the modified Rankin scale at 3 months post-EVT, with a modified Rankin scale score below 3 indicating a favorable outcome.There was an independent correlation between PH and unfavorable outcomes (odds ratio [OR]: 6.66, 95% CI: 1.46-31.08, P = .016). Phase at 2-3 days post-EVT was significantly associated with PH (P = .045). Δphase (OR: 0.91, 95% CI: 0.94-0.99, P = .014) was an independent factor of PH. The optimal Δphase cutoff was -10°, with an area under the curve of 0.715 (sensitivity 82.6%, specificity 70.0%, P = .043).Poor results in acute ischemic stroke patients after EVT are independently predicted by PH. Modifications to dCA from 24 hours to 2-3 days post-EVT may be a novel marker for PH.Copyright © Congress of Neurological Surgeons 2025. All rights reserved.