OBJECTIVE Observation and neurosurgical intervention for unruptured intracranial aneurysms (UIAs) in the elderly population is rapidly increasing. Cerebral aneurysm coiling (CACo) is favored over cerebral aneurysm clipping (CAC) in elderly patients, yet some elderly individuals still undergo CAC. The cost-effectiveness of treating UIAs requires further exploration. Understanding the effect of intervention on hospital charges and length of stay (LOS) as well as perioperative mortality and complications can further shed light on its economic impact. The purpose of this study was to analyze the cost and perioperative outcomes of UIAs in elderly patients (? 65 years of age) after CACo or CAC intervention. METHODS Retrospective cohorts of CACo and CAC admissions were extracted from National (Nationwide) Inpatient Sample data obtained between 2002 and 2013, forming parallel intervention groups to compare the following outcomes between elderly and nonelderly patients: average LOS and mean hospital admission costs, in-hospital mortality, and complications. Covariates included sex, race or ethnicity, and comorbidities. RESULTS Elderly patients undergoing CAC experienced an average LOS of 8.0 days, whereas elderly patients undergoing CACo stayed an average of 3.2 days. The mean hospital charges incurred during admission totaled $95,960 in the elderly patients who underwent CAC versus $87,960 in the ones who underwent CACo. Elderly patients in whom CAC was performed had a 2.2% rate of in-hospital mortality, with a 2.6 greater adjusted odds of in-hospital mortality than nonelderly patients treated with CAC. In contrast, elderly patients who underwent CACo had a 1.36 greater adjusted odds of in-hospital mortality than their nonelderly counterparts. Compared to nonelderly patients receiving both interventions, elderly individuals had a significantly higher prevalence of various comorbidities and incidence of complications. Elderly patients who received CAC experienced a 10.3% incidence rate of perioperative stroke, whereas their CACo counterparts experienced this complication at a rate of 3.5%. Elderly patients treated with CAC had greater odds of perioperative acute renal failure, whereas their CACo counterparts had greater odds of perioperative deep venous thrombosis and pulmonary embolism. CONCLUSIONS Intervention with CAC and CACo in the elderly is resource intensive and is associated with higher risk than in the nonelderly. Those deciding between intervention and conservative management should consider these risks and costs, especially the 2.2% postoperative mortality rate associated with CAC in the elderly population. Further comparative cost-effectiveness research is needed to weigh these costs and outcomes against those of conservative management.