Objective: To retrospectively investigate the spectrum of diagnoses in patients who presented with presumed transverse myelitis (TM) seen at a specialized center dedicated to TM care. Background: TM is an inflammatory neurologic disorder that causes damage to motor and sensory tracts of the spinal cord. The cause of TM is variable and often never discovered. Patients may experience any combination of weakness, altered sensation, bowel and bladder dysfunction and dysautonomia. Non-immunologic myelopathies may cause a similar clinical presentation. As such, investigation is paramount to ensure appropriate treatment. Design/Methods: We conducted a retrospective analysis of new patients referred to the Johns Hopkins TM Center (JHTMC) between 2010 and 2017. We reviewed the clinical/temporal profile, neuroimaging and laboratory assessment to establish a final diagnosis. Results: One thousand patients were included in this analysis (66% White/Caucasian descent; 60% female), of which 62% were confirmed to have an inflammatory cause for their myelopathy, of which 35% was idiopathic. An additional 41% was attributable to an underlying disease such as multiple sclerosis or neuromyelitis optica spectrum disorder. However, 24% of patients who were initially diagnosed with TM were found to have non-inflammatory causes of myelopathy, including vascular abnormalities (38%) and compressive myelopathy (24%). Ten percent of cases had inadequate initial evaluations or follow-up, and a final diagnosis could not be established. Conclusions: One quarter of patients initially referred to the JHTMC for the diagnosis of TM were found to have a non-myelopathic cause for their symptoms. Furthermore, of those with inflammatory TM, 41% had an underlying disease for which long-term immunotherapy was warranted. This analysis of a large cohort of patients suggests that a more detailed analysis at acute presentation is necessary to ensure patients receive adequate and timely treatment of the underlying cause of myelopathic symptoms towards the effort of improving patient outcomes. Disclosure: Dr. Mealy has nothing to disclose. Dr. Munoz-Arcos has nothing to disclose. Dr. Barreras has nothing to disclose. Dr. Garcia has nothing to disclose. Dr. Becker has nothing to disclose. Dr. Newsome has nothing to disclose. Dr. Gailloud has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Codman Neurovascular. Dr. Levy has nothing to disclose. Dr. Pardo-Villamizar has nothing to disclose.