Context: More than 1.6 million sport-related concussions occur every year in the United States, affecting greater than 5% of all high school athletes who participate in contact sports. As more females participate in sports, understanding possible differences in concussion symptoms between sexes becomes more important.Objective: To compare symptoms, symptom resolution time, and time to return to sport between males and females with sport-related concussions.Design: Descriptive epidemiology study. Setting: Data were collected from 100 high schools via High School RIO (Reporting Information Online).Patients or Other Participants: Athletes from participating schools who sustained concussions while involved in interscholastic sports practice or competition in 9 sports (boys' football, soccer, basketball, wrestling, and baseball and girls ' soccer, volleyball, basketball, and softball) Main Outcome Measure(s): Reported symptoms, symptom resolution time, and return-to-play time.Results: No difference was found between the number of symptoms reported (P 5 .30). However, a difference was seen in the types of symptoms reported. In year 1, males reported amnesia (exact P 5 .03) and confusion/disorientation (exact P 5 .04) more frequently than did females. In year 2, males reported more amnesia (exact P 5 .002) and confusion/ disorientation (exact P 5 .002) than did females, whereas females reported more drowsiness (exact P 5 .02) and sensitivity to noise (exact P 5 .002) than did males. No differences were observed for symptom resolution time (P 5 .40) or return-to-play time (P 5 .43) between sexes.Conclusions: The types of symptoms reported differed between sexes after sport-related concussion, but symptom resolution time and return-to-play timelines were similar.