<h3>BACKGROUND CONTEXT</h3> Increased operative duration, in addition to time under anesthesia, has been shown to increase the risk of intraoperative and postoperative complications. The specific relationship between operating room size and prolonged surgical duration in spine surgery has yet to be explored. <h3>PURPOSE</h3> To determine if operating room (OR) size is independently associated with extended duration of spine surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study. <h3>PATIENT SAMPLE</h3> All patients over age 18 who underwent any primary or revision decompression or fusion for degenerative spinal pathologies at a single academic institution were retrospectively identified. Patients with a traumatic injury, infection, malignancy, or incomplete surgical timing parameters were excluded. <h3>OUTCOME MEASURES</h3> Surgical case extension. Surgical case delay. <h3>METHODS</h3> A retrospective cohort analysis of patients undergoing spine surgery for degenerative pathologies at a high-volume academic center was performed. Operating room timing parameters including theater time, duration under anesthesia, and procedural time were recorded. Surgical case delay and surgical case extension were calculated through deviations from the scheduled case start time and expected case duration. Operating rooms were dichotomized into large and small groups based on size above or below mean square footage. Univariate analysis compared patient demographics and surgical factors across large and small OR groups. The relationship between OR size and minutes of case delay and case extension was evaluated. <h3>RESULTS</h3> A total of 4,178 patient surgeries met the inclusion criteria. Patient demographics, medical comorbidities, and surgical characteristics did not vary meaningfully between large and small OR groups. Patients undergoing surgery in large ORs experienced significantly greater prolongation in case duration (actual theater time - scheduled theater time). When cases with extended duration were compared to equivalent cases adhering to expected duration parameters, procedure time and time under anesthesia remained significantly greater in large operating rooms. Extension in theater time was found to vary independently from delay in surgical start time as delay time was statistically equivalent between OR groups. <h3>CONCLUSIONS</h3> Spine surgery in larger ORs was shown to correlate with extended procedural duration. Larger operating rooms may decrease surgical efficiency. Further research is required to determine if operating size independently predicts prolonged surgery and adverse outcomes. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.