Abstract:Aneurysm surgery is increasing day by day in our country but the exact timing of surgery is still controversial. Introduction:Aneurysms resemble bubbles or focal dilation of arteries that occur at weak points of the artery wall ( figure-1). There are many factors for its formation. These factors include genetic predisposition, the anatomy of the artery and its branches, 'wear-and-tear' on the wall of the arteries due to blood flow, artery disease and cigarette smoking 1 . Aneurysms are the most common at circle of Willis in the central skull base. Approximately 80% of aneurysms arise from anterior circulation of the brain, while 20% form posterior circulation of the brain 1.2 .