ntroduction Simulation has become an established method for education and training of Emergency Medical Services personnel in different skills such as advanced airway techniques, also in evaluation and initial care of stroke patients and in pre - hospital trauma. Simula tion can be a useful method to improve learning. To our knowledge, there are only a few studies that relate simulation to the effect on clinical skills. The aim of the present study was to investigate the effect of simulation on the clinical competence in a pre - hospital trauma care course for ambulance nurses. Methods The study was performed using a before - after design. Seventeen ambulance nurse students who participated in a trauma care course were evaluated in two simulated trauma cases. All subjects had passed the initial theoretical part of the course. The pre - test was performed in the beginning of the following part of the course involving simulation and the post - test at the end of the course. The analysis was performed by assessment of performance, as seen on video - tapes from the pre - tests and the post - tests. A validated instrument was used to determine the level of student’ s clinical competence. Paired t - test was used to confirm differences between the pre - test and post - test results . Results There was a significant increase in the over - all results for the post - test, with a difference of 1.12 points (t=4.642, df=16, p= 0.001) Situation Awareness, Patient Assessment and Decision Making showed the most pronounced improvements. Conclusion The results imply t hat simulation in addition to traditional theoretical education improves the clinical competence of the students, in comparison to traditional education and training without any significant amount of simulation.