The majority of head injuries in rugby union occur during tackles in which the head receives an impact. Head impacted tackles may be a result of poor tackle technique. Therefore, the purpose of this study was to analyse ball-carrier and tackler technique proficiency in head impacted tackles and compare the technique proficiency to successfully completed tackles in real-match situations.Retrospective video analysis.Video footage of head impacts with the ‘head impacted player’ (n=157) and the opposing player ‘impacting player’ (n=156) were scored for contact technique using a list of technical criteria and compared to contact technique scores of role and tackle-type matched injury-free, successful tackles (n=170).Ball-carriers contacting their head during front-on head impacted tackles (mean 6.4, 95%CI 5.6–7.1 AU, out of a total score of 14) scored significantly less than the ‘impacting player’ (mean 8.1, 95%CI 7.1–9.1 AU, p<0.01, ES=0.5, small) and successful ball-carriers (successful ball-carrier mean 9.4, 95%CI 8.9–9.9 AU, p<0.0001, ES=1.1, moderate). Tackler contact proficiency scores during successful front-on tackles (mean 12.3, 95%CI 11.6–12.9 AU, out of a total score of 16) were significantly greater than tackler contact proficiency scores for the ‘head impacted player’ (mean 9.8, 95%CI 8.6–10.9, p<0.001, ES=0.8, moderate) and ‘impacting player’ (mean 9.3, 95%CI 8.4–10.1, p<0.0001, ES=1.0, moderate).Both the ball-carrier and tackler have a technical deficiency when there is a head impact in matches. The implication of this finding is that players and coaches need to acknowledge that both the ball-carrier and tackler are responsible for each other’s safety during the tackle.