OBJECTIVE Most patients suffering from aneurysmal subarachnoid hemorrhage (aSAH) initially present to a hospital that lacks a neurosurgical unit. These patients require interhospital transfer (IHT) to tertiary facilities capable of multidisciplinary neurosurgical intervention. Yet, little is known about the effects of IHT on the outcomes of patients suffering from aSAH. In this study, the authors examined the effects of IHT and transport method on the timing of treatment, rebleed rates, and overall outcomes of patients who have experienced aSAH. METHODS A retrospective review of medical records identified all consecutive patients who presented with aSAH at an outside hospital and subsequently underwent IHT to a tertiary aneurysm care center and patients who initially presented directly to a tertiary aneurysm care facility between 2008 and 2015. Demographic, operative, radiological, hospital of initial evaluation, transfer method, and outcome data were retrospectively collected. RESULTS The authors identified 763 consecutive patients who were evaluated for aSAH at a tertiary aneurysm care facility either directly or following IHT. For patients who underwent IHT and after accounting for these patients' clinical variability and dichotomizing the patients into groups transferred less than 20 miles and more than 20 miles, the authors noted a significant increase in mortality rates: 7% (< 20 miles) and 18.8% (> 20 miles) (p = 0.004). The increased mortality rate was partially explained by an increased rate of initial presentation to an accredited stroke center in patients undergoing IHT of less than 20 miles (p = 0.000). The method of transport (ground or air ambulance) was found to have significant effect on the patients' outcomes as measured by the Glasgow Outcome Scale score (p = 0.021); patients who underwent ground transport demonstrated a higher likelihood of discharge to home (p = 0.004). The increased severity of presentation in the patient cohort undergoing IHT by air as defined by the Glasgow Coma Scale score, a need for an external ventricular drain, Hunt and Hess grade, and intubation status at presentation did not result in increased mortality when compared with the ground cohort (p = 0.074). In addition, there was an 8-hour increase in duration of time from admission to treatment for the air cohort as compared with the ground cohort (p = 0.054), indicating a potential for further improvement in the overall outcome of this patient group. CONCLUSIONS Aneurysmal SAH remains a challenging neurosurgical disease process requiring highly coordinated care in tertiary referral centers. In this study, the overall distance traveled and the transport method affected patient outcomes. The time from admission to treatment should continue to improve. Further analysis of IHT with a focus on patient monitoring and treatment during transport is warranted.