Background: High school athletes are at risk for concussions. Although a previously published study showed an increase in concussion rates for a single school district, it remains unknown if the rate of concussions among high school athletes is increasing nationally. Purpose: To investigate national high school athlete concussion rates over time. Study Design: Descriptive epidemiologic study. Methods: The rate of concussions per 1000 athlete-exposures was calculated for academic years 2005-2006 through 2011-2012 using the High School Reporting Information Online sports injury surveillance system. Results: During the 7-year period of this study, High School Reporting Information Online captured 4024 concussions with overall concussion diagnosis rates increasing significantly from 0.23 to 0.51 (P = .004). Concussion diagnosis rates increased for each of the 9 sports studied, with 5 sports having statistically significant increases over this 7-year period. Conclusion: The study analysis indicates that national concussion diagnosis rates for high school sports have increased significantly over time.