Background: Hiring athletic trainers (ATs) in high schools has attracted rising interest as a potential way of improving adolescents' health by enhancing their safety and reducing their risk of injury.Objective: This study aims to determine if there is a difference in the referral patterns, injury diagnoses, and injury treatments performed at a metropolitan high school when an AT is employed versus not employed by the school.Design: This is a retrospective quantitative two-period study.Setting: The study was conducted in the high school athletic department in Norfolk, Virginia, and the study population was high school athletes (age 14-18).Main outcome measures: Changes in referral patterns, injury diagnoses, and injury treatments performed at a local high school when an AT is employed versus not employed by the school; specifically, we examined the number of and percent changes in yearly treatments, referrals, evaluations, and re-evaluations during the two periods.Results: Our first t-test revealed a statistically significant increase in the number of reported injuries