Despite progress in the understanding of risk factors for aneurysm rupture, the decision whether or not to treat an unruptured intracranial aneurysm (UIA) should be treated remains a challenge. A multidisciplinary team of neurovascular surgeons and interventional radiologists with broad experience in the field should make this decision under critical consideration of their own skills, complication rates and treatment outcomes. Preventive aneurysm occlusion should be proposed whenever the risk of the natural course is estimated higher than the risk associated with the treatment. While the treatment risks have been well documented, a growing body of literature nowadays guides the physician to estimate the risk of aneurysmal subarachnoid hemorrhage from an UIA. Scores like the PHASES score somewhat facilitate the estimation of the rupture risk and prove helpful for the discussion with the patient – whether to treat or whether to follow the aneurysm.