Background: Medial ulnar collateral ligament (UCL) injuries of the elbow that require surgical management are uncommon. There is growing evidence, however, suggesting that the incidence of UCL reconstruction (UCLR) procedures is rapidly increasing. We sought to quantify the incidence of age-related trends for UCLR from 2003 to 2014 and subsequently to project future trends through 2025. We hypothesized that as the total number of UCLRs performed increased, a disproportionate incidence among younger patients would be observed. Methods: New York State's Statewide Planning and Research Cooperative System database was queried from 2003 to 2014 to identify individuals between 10 and 40 years old undergoing UCLR. Poisson regression was used to develop future projections for UCLR and New York State population through 2025, and incidence estimates per 100,000 people were calculated. Results: In New York State between 2003 and 2014, there were 890 patients who underwent UCLR, with average annual incidence per 100,000 people equaling 6.3 +/- 2.8 for ages 15 to 19 years, significantly greater than for all other age groups (P < .001). Projections from 2015 through 2025 suggest that incidence in 15- to 19-year-olds and 20- to 24-year-olds will continue to rapidly increase while rates for other age groups will remain relatively stable. Conclusions: The number of UCLRs performed between 2003 and 2014 increased by 343%, and a disproportionate trend in average annual incidence for patients between 15 and 19 years old was observed. As our review of the literature questioned outcomes in adolescent athletes after UCLR, continued attempts at preventing these injuries in the young throwing athlete remain paramount. (C) 2016 Journal of Shoulder and Elbow Surgery Board of Trustees.