Summary:The rationale for radical surgery to treat unruptured cerebral aneurysms (uAN) remains unclear. Most investigations of evidence-based medicine (EBM) have focused on prognostic factors such as the natural history, surgical outcome, risk-benefit analysis, and socioeconomic effects, and not on patient factors such as decision-making, anxiety, or satisfaction. However, the number of legal cases focusing on complications caused by examination or surgical intervention has increased in Japan. Further, deterioration of quality of life in patients diagnosed with uAN has also become evident. In this study, we surveyed patient satisfaction (PS) in 197 patients who underwent clipping surgery or coil embolization during the last 7 years, using a mail questionnaire sent by a third party.We review the rationale for the treatment of uAN, and discuss the necessity of a paradigm shift of rationale from treatment based on EBM to treatment that is tailor-made.The total response rate was 69.5%. A visual analogue scale analyzing PS revealed no significant difference among clip, coil and observation groups. The most striking data was that PS in the patient group who had received clipping surgery for incidentally discovered AN, varied more than we had projected irrespective of no deterioration of neurological and intellectual status evaluated by Wechsler Adult Intelligence Scale-Revised and Wechsler Memory Scale. These results indicate that PS might be highly affected by patients' own personality.