Background/aim Sport-related concussion is associated with various short- and long-term health consequences, especially among adolescent athletes. Yet, many concussions go unreported and/or unrecognised. The purpose of this study was to assess high school athletes' concussion-related knowledge, attitudes, intentions and reporting behaviours, and to explore whether gender differences are evident. Methods A total of 435 high school athletes (52.2% female; mean age, 14.55 ± 1.67 years) participated in the survey. Questions assessed athletes' knowledge, attitudes, reporting intention and reporting behaviours, in respect to sports-related concussion. Comparisons between male and female athletes were explored using Mann-Whitney tests and chi-squared (¿2) tests as appropriate. Results We found that 60% of the participants stated that they have played in practice or during a game (this season) with concussion symptoms. Males expressed more negative outcomes of concussion reporting and lower concussion reporting intention, compared to females. We found no significant gender differences in concussion-reporting behaviours. Conclusion Our findings suggest that knowledge, favourable attitudes towards reporting and reporting intention alone are not enough to create an environment that encourages the disclosure of concussion symptoms. Health promotion communication campaigns, coupled with concussion education and awareness programmes, should be utilised to further highlight the importance of timely concussion management, and to create a culture in which the reporting of concussion is considered normative.