Background: In the Netherlands, each year a three-day international multidisciplinary trauma masterclass is organized to provide the knowledge and skills needed to care for critically injured trauma patients. This study was designed to longitudinally evaluate the effect of the course on participant’s self-assessment of their own ability and confidence to perform general and specific skills. Methods: Between 2013 and 2016, all participants were invited to complete a questionnaire before and during follow-up. Participants were asked to self-assess their level of confidence to perform general skills (communication, teamwork, leadership) and specific skills. Mean scores were calculated, and mixed models were used to evaluate correlation. Results: We asked 265 participants to participate. Response rate was 64% for the pre-questionnaire, 63% for the post-questionnaire and for 3 months, 1 year and 2 years, respectively, 40%, 30%, 20%. The surgical group showed a statistically significant increase in self-assessed confidence for general skills (3.82–4.20) and specific technical skills (3.01–3.83; p < 0.001). In the anesthetic group, self-assessed confidence increased significantly in general skills (3.72–4.26) and specific technical skills (3.33–4.08; p < 0.001). For both groups statistical significance remained during follow-up. Conclusions: This study demonstrated a sustained positive effect of a dedicated multidisciplinary trauma training curriculum on participant’s self-assessed confidence to perform both general and specific technical skills necessary for the care of injured patients. Given the known association between confidence and competence, these findings provide evidence that dedicated trauma training curricula can provide positive lasting results. Level of evidence: This is a basic science paper and therefore does not require a level of evidence.