A 26-year-old young man, had Graves' disease in hyperthyroid state, presented with frequent episodic transient left hemiparesis and mild slurred speech lasting for few minutes to 2 hours for one month. Infarction at posterior limb of right internal capsule was found on brain MRI. Angiography revealed multiple intracranial arteries stenoses around the circle of Willis. After treatment with propylthiouracil and aspirin, his thyroid function returned to normal and the patient remained free from stroke.