A 45-year-old Chinese man presented with acute severe headache for 2 days. He was diagnosed as subarachnoid hemorrhage. Head CT and subsequent head digital subtraction angiography (DSA) showed left internal carotid artery (ICA) aneurysm in the supraclinoid segment. Stent-assisted coil embolization of aneurysm was performed. Three hours after the surgery, the patient was found to be drowsy and with paralysis of the right limb and slurred speech. Urgent head CT examination ruled out acute hemorrhage; however, DSA showed acute thrombosis in the left ICA between the branches of the ophthalmic artery and middle cerebral artery, which was probably from an acute in-stent thrombosis. Urokinase (100,000 units) was given through a micro-tube but failed to dissolve the thrombus; thus, stent embolectomy was performed, which successfully removed the thrombus. Repeat angiography showed that the left ICA was completely recanalized. Postoperatively, the patient regained consciousness and was well-limbed and fluent in speech. No neurological symptoms or signs were found at 6-, 12-, and 24-month follow-up.