Giant aneurysms and some basilar aneurysms can cause some problems due to their size and clot formation within them. Recently, profound hypothermia and barbiturate cerebral protection were used for successful surgical treatment of these complex intracranial vascular lesions. We experienced a female patient with a giant anterior aneurysm. After femoral arterial and venous cannulation, cardiopulmonary bypass was performed and the aneurysm was clipped under a state of deep hypothermic circulatory arrest. However, she developed postoperative brain swelling and coma and died due to respiratory failure in ICU.