BACKGROUND CONTEXT Lumbar microdecompression is one of the most common procedures in orthopedic spine surgery with an overall low complication and high satisfaction rate. The procedure is typically performed with visualization aids, either loupes or an operating room microscope. Several studies to date have investigated differences between these two magnification tools, with conflicting results. Some authors argue in favor of the microscope, citing improved visualization, better ergonomics and improved patient outcomes, while others argue that its use makes no clinical difference. These studies consist primarily of small patient cohorts numbering 50-100 subjects. PURPOSE The purpose of this study is to determine how the routine use of an operating room microscope during single level lumbar microdecompression impacts intraoperative and short-term surgical outcomes through an examination of the largest retrospective cohort to date. STUDY DESIGN/SETTING Retrospective review of American College of Surgeons National Surgical Quality Improvement Project (ACS-NSQIP) database. PATIENT SAMPLE A total of 43,948 patients who underwent single level lumbar microdecompression from 2005 to 2015. OUTCOME MEASURES Assessment of surgical benchmarks of operative time and length of hospital stay as well as differences in early (30 day) complication rates. The specific complications evaluated included the need for blood transfusion, return to the operating room, pulmonary embolism, deep venous thrombosis, sepsis, cerebrovascular accident, cardiac arrest, ventilator time greater than 48 hours, urinary tract infection, pneumonia, myocardial infarction, surgical site infections, and patient mortality. METHODS Using the ACS-NSQIP database, we identified all patients who underwent single level lumbar microdecompression (CPT 63030). They were divided into two cohorts, those cases that involved the use of an operating room microscope (CPT 69990), and those that did not. We compared intraoperative and postoperative procedural data as well as the incidences of local and systemic complications. RESULTS The ACS-NSQIP database identified 43,948 patients who underwent single level lumbar microdecompression from 2005 to 2015. Of that patient cohort 4,654 cases included the use of an operating room microscope. There were no clinically significant demographic differences between patient cohorts. We identified clinically important statistical differences in length of stay (1.37 vs. 1.75 days, p CONCLUSIONS The routine use of an operating room microscope in single level lumbar microdecompression does not affect short-term patient outcomes. Importantly, there is no difference in mean operative time or infection rate with the addition of a microscope. There is a statistically significant trend toward decreased length of stay and fewer blood transfusions in the microscope cohort; however, in the setting of a large database study and small absolute differences, the clinical implications of these findings are difficult to interpret. Based on these results, we conclude that the decision to use an operating room microscope in single level lumbar microdecompression should be left to the treating surgeon and based upon considerations of improvements in visualization, surgeon ergonomics and ability to educate surgical assistants. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.