목적: Endoscopic trans-sphenoidal surgery (TSA) is emerging as a minimally invasive and maximally effective procedure for pituitary tumor. Despite lower complication rate of TSA, all the time, there is risk of vascular complication during TSA and vascular complication can lead to mortality and serious morbidity. This study was designed to present usefulness of carotid CT angiography as pre-operative evaluation before endoscopic TSA. 방법:We retrospectively studied 207 patients who underwent carotid CT angiography and OMU CT before planning endoscopic TSA due to pituitary tumor between April 2012 and December 2014. 결과:There is no difference between CT angiography and OMU CT for finding sinus evaluation. And 23 patients were found to have aneurysm in pre-operative CT angiography. Of the 23 patients, 18 had aneurysm in internal carotid artery, 2 in anterior communicating artery, each 1 in superior cerebellar artery, middle cerebellar artery, and ophthalmic artery. Finally, 6 patients underwent trans-femoral cerebral angiography(TFCA) or embolization before TSA and 4 patients cancel surgery due to risk of vessel injury. 결론:Carotid CT angiography is equal to OMU CT for evaluating sinus and can find incidental aneurysm that can lead to serious vessel injury, It enable surgeon to make preparation for unexpected risk as aneurysm. So OMU CT can be substituted for Carotid CT angiography as pre-operative evaluation before endoscopic TSA