OBJECTIVE The impact of treatment method surgical clipping or endovascular coiling on the cost of care for patients with aneurysmal subarachnoid hemorrhage (SAH) is debated. Here, the authors investigated the association between treatment method and long-term Medicare expenditures in elderly patients with aneurysmal SAH. METHODS The authors performed a cohort study of 100% of the Medicare fee-for-service claims data for elderly patients who had undergone treatment for ruptured cerebral aneurysms in the period from 2007 to 2012. To control for measured confounding, the authors used propensity score adjusted multivariable regression analysis with mixed effects to account for clustering at the hospital referral region (HRR) level. An instrumental variable (regional rates of coiling) analysis was used to control for unmeasured confounding by creating pseudo-randomization on the treatment method. RESULTS During the study period, 3210 patients underwent treatment for ruptured cerebral aneurysms and met the inclusion criteria. Of these patients, 1206 (37.6%) had surgical clipping and 2004 (62.4%) had endovascular coiling. The median total Medicare expenditures in the 1st year after admission for SAH were $113,000 (IQR $77,500 $182,000) for surgical clipping and $103,000 (IQR $72,900 $159,000) for endovascular coiling. When the authors adjusted for unmeasured confounders by using an instrumental variable analysis, clipping was associated with increased 1-year Medicare expenditures by $19,577 (95% CI $4492 $34,663). CONCLUSIONS In a cohort of Medicare patients with aneurysmal SAH, after controlling for unmeasured confounding, surgical clipping was associated with increased 1-year expenditures in comparison with endovascular coiling.