Although Guglielmi Detachable Coil (GDC) endovascular treatment of intracranial aneurysms has become an alternative to surgery, the main complication continues to be thromboembolic events. In our patient, we found thrombus at the third branch of the right middle cerebral artery after coil embolization. We added intravenous heparin and gave abciximab, an antiplatelet agent through the catheter. We then elevated the blood pressure and administered intravenous colloid solution to maintain adequate collateral circulation. One day later, the patient presented with acute focal infartion in the right frontal lobe and we treated her with low molecular weight heparin. After seven days, the patient's symptoms disappeared, and there was no residual neurological deficit. Therefore, we believe potential clinical complications can be avoided through early recognition of thrombus and appropriate medical therapy. Furthermore, it is necessary to prevent hypotension and to maintain proper hematocrit levels during operations in patients having risk factors for thrombosis.