BACKGROUND: Youth rugby players represent 45.2% (N = 69,472) of the Irish rugby union playing population. The risk and consequences of concussion injury are of particular concern in these young athletes, but limited epidemiological data exists. This study investigated annual and lifetime prevalence of concussion in an Irish schoolboy rugby union cohort. METHODS: An anonymous cross-sectional survey of youth rugby players was conducted. Diagnosed concussion was defined as an incident where diagnosis was confirmed by a health professional or coach. Demographics, prevalence, and attitudes to concussion were collated. Data were analyzed with descriptive statistics, chi-square test, t-tests, Mann-Whitney tests, and logistic regression. RESULTS: Overall, 304 youth (aged 12-18 years) responded. Lifetime prevalence of diagnosed concussion was 19.4%, with annual (2010) prevalence 6.6%. Approximately 25.4% of players with diagnosed concussions returned to play without medical advice. Internal motivation (11.8%) was the predominant factor in feeling pressure to play while concussed. A desire for further concussion education was expressed by 89.5% of participants. CONCLUSIONS: Reform is required to prevent and manage concussion injuries among youth players in the rugby union, including mandatory education specific to concussion and implementation of return-to-play protocols. These findings have relevance for governing bodies, coaches, clinicians, schools, parents, and rugby union players.