Background and Purpose— Unruptured intracranial aneurysms (UIAs) are being identified more frequently and endovascular coil embolization has become an increasingly popular treatment modality. Our study evaluates patient outcomes with changing patterns of treatment of UIA. Methods— We conducted a retrospective, longitudinal cohort study of 3132 hospital discharges for UIA identified from the New York Statewide Database (SPARCS) in 2005 to 2007 and 2200 discharges from 1995 to 2000. The rates of endovascular coiling and surgical clipping were examined along with hospital variables and discharge outcome. Anatomic specifics of UIA were unavailable for analysis. Results— The case rate for treatment of UIA doubled from 1.59 (1995 to 2000) to 3.45 per 100 000 (2005 to 2007, P <0.0001) and increased in the case treatment rate for coiling of UIA (0.36 versus 1.98 per 100 000, P <0.0001). Compared with the old epoch, there were more UIAs clipped at high-volume centers (55.8% versus 78.8%, P <0.0001) but fewer coiled at high-volume centers (94.8% versus 84.5%, P <0.0001) in the new epoch. Coiling and increasing hospital UIA treatment volume were associated with good discharge outcome. However, there was no significant improvement in overall good outcome when comparing 1995 to 2000 versus 2005 to 2007 (79% versus 81%, P =0.168) and a worsening of good outcomes for clipping (76.3% versus 71.7%, P =0.0132). Conclusions— Despite coiling being associated with an increased incidence of good outcome relative to clipping of UIA, the increase in coiling has failed to improve overall patient outcome. The shift in coiling venue from high-volume centers to low-volume centers and decreasing microsurgical volume accompanied by a worsening in microsurgical results contribute to this. This argues for greater centralization of care.