Background: There is widespread consensus on the importance of safe and secure communication in healthcare, especially in trauma care where time is a limiting factor. Although non-verbal communication has an impact on communication between individuals, there is only limited knowledge of how trauma team leaders communicate. The purpose of this study was to investigate how trauma team members are positioned in the emergency room, and how leaders communicate in terms of gaze direction, vocal nuances, and gestures during trauma team training. Methods: Eighteen trauma teams were audio and video recorded during trauma team training in the emergency department of a hospital in northern Sweden. Quantitative content analysis was used to categorize the team members' positions and the leaders' non-verbal communication: gaze direction, vocal nuances, and gestures. The quantitative data were interpreted in relation to the specific context. Time sequences of the leaders' gaze direction, speech time, and gestures were identified separately and registered as time (seconds) and proportions (%) of the total training time. Results: The team leaders who gained control over the most important area in the emergency room, the "inner circle", positioned themselves as heads over the team, using gaze direction, gestures, vocal nuances, and verbal commands that solidified their verbal message. Changes in position required both attention and collaboration. Leaders who spoke in a hesitant voice, or were silent, expressed ambiguity in their non-verbal communication: and other team members took over the leader's tasks. Discussion: In teams where the leader had control over the inner circle, the members seemed to have an awareness of each other's roles and tasks, knowing when in time and where in space these tasks needed to be executed. Deviations in the leaders' communication increased the ambiguity in the communication, which had consequences for the teamwork. Communication cannot be taken for granted; it needs to be practiced regularly just as technical skills need to be trained. Simulation training provides healthcare professionals the opportunity to put both verbal and nonverbal communication in focus, in order to improve patient safety. Conclusions: Non-verbal communication plays a decisive role in the interaction between the trauma team members, and so both verbal and non-verbal communication should be in focus in trauma team training. This is even more important for inexperienced leaders, since vague non-verbal communication reinforces ambiguity and can lead to errors.