Background The anti‐COVID‐19 vaccines are new, and we should be alert of potential adverse effects of them. Aims of the Study To report a case of a large hemorrhagic stroke 5 days after ChAdOx1 nCoV‐19 vaccination. Methods Clinical, imaging, and laboratory data of a patient with stroke admitted to our emergency department. Results A woman, 57 years old, took the first dose of the ChAdOx1 nCoV‐19 vaccine and shortly thereafter presented mild systemic symptoms and started on aspirin. On day 5, she had a sudden onset of sweating and paleness, which has followed by left hemiparesis, vomiting, and somnolence. Computed tomography showed a large right deep frontal lobe parenchymal hematoma with the inundation of the entire ventricular system. Platelets count, fibrinogen, prothrombin time, and D‐dimer were normal. Digital subtraction angiography did not show any signs of thrombosis or aneurysms in brain circulation. Conclusions Clinicians should be aware of cerebrovascular adverse effects of ChAdOx1 nCoV‐19, including out‐of‐context of vaccine‐induced immune thrombotic thrombocytopenia.