Background:As participation and specialization in youth sports has increased, so too has the incidence of overuse conditions, such as medial epicondyle apophysitis, or Little League Elbow (LLE). Hypothesis/ Purpose: The study purpose was to assess the demographic features, clinical presentation, management, and outcomes of a population of skeletally immature athletes with this increasingly common, but understudied, condition.Methods:A retrospective analysis was performed of patients diagnosed with LLE between 2003 and 2017 at a tertiary-care pediatric hospital. All patients had open apophyses with a clinical history of repetitive overhead athletic activity and radiographic and/or physical exam findings consistent with LLE. Study variables were derived from the electronic medical record.Results:Three hundred seventeen subjects (mean age: 12.8 years, range 8yrs – 16yrs; 310 males, 98%) were identified. The vast majority were baseball players (n=310, 98%), though there were several tennis players (n=4, 1%) and football quarterbacks (n=3, 1%). Two-hundred sixty-eight patients (85%) presented with apophysitis, while 49 (15%) presented with acute avulsion fractures from throwing (with 84% reporting preceding medial elbow pain). The acute fracture patients are the subject of a separate study. In the apophysitis cohort, all of whom presented with medial elbow pain, other presenting findings/symptoms included decreased elbow range of motion (16%) and concomitant ipsilateral shoulder pain (13%). Amongst those with documented shoulder exams, a majority (55%) demonstrated glenohumeral internal rotation deficit (GIRD) with a significantly longer time from diagnosis to resolution of symptoms (p=0.025). All apophysitis patients were treated with rest (complete cessation 75%, relative rest/position change 25%). Mean follow up was 32 months (sd 33 months). Return to sports occurred at a median of 12 weeks from diagnosis (IQR 7wks – 18wks). Recurrence of elbow pain occurred a median of 24 months (IQR 11mo - 43mo) following initial diagnosis in 13% of patients, a sub-cohort with significantly longer duration of symptoms prior to index presentation (p=0.024). One patient also suffered a subsequent medial epicondylar avulsion fracture while throwing in the setting of non-compliance with recommended rest.Conclusion:Little League Elbow is most commonly seen in adolescent and pre-adolescent male pitchers but may rarely be seen in other overhead athletic sub-populations. Careful evaluation of the entire kinetic chain is critical to identify concomitant pathology such as GIRD, which may portend a prolonged recovery. Proper treatment is necessary to minimize recurrence and development of epicondyle avulsion fractures, which represent a potentially preventable, but severe variant of LLE.