The lumbar puncture (LP) is a common procedure in the pediatric emergency department. A retrospective review was conducted of patients who had LPs from 2012 to 2016 at 2 children's hospitals to (1) characterize medication use during the pediatric LP and (2) test the hypothesis that varied medication use influences LP outcome. Outcomes were defined as unsuccessful if the LP was documented as unsuccessful, had a cerebrospinal fluid (CSF) red blood cell (RBC) count >400 cells/µL, or if a second LP was performed within 24 hours. In total, 8463 patients were reviewed and 2806 (33%) were included in the study. We noted significant variation in LP medication use. When adjusted for patient demographics, location, weight, position, and provider experience, our regression model revealed that the use of fentanyl, ketamine, nitrous oxide, and propofol were best associated with LP success. These data suggest the need for a standardized LP medication protocol as provider choice in medication significantly influences LP outcome.