Introduction:Mass-casualty incidents (MCI) featuring a large number of injured persons caused by human-made or by natural disasters are increasing globally. During these incidents, medical first responders (MFR) need to take appropriate action that saves lives. In this context, the adage “practice makes perfect” is befitting to MCI training. However, providing large-scale MCI training is often difficult due to the significant effort required to create these types of exercises. Drawbacks include a large number of actors needed to portray victims, availability of infrastructure, and realistic treatments. Virtual Reality (VR) has been demonstrated in several domains to be a serious alternative, and in some areas also a significant improvement to conventional training. As an advanced alternative to VR, Mixed Reality (MR) have the potential to provide a dynamic simulation of an VR environment and hands-on practice on injured victims.The aim is: 1) to present insights of a newly developed MR training system for increasing MCI preparedness and 2) discuss pedagogical aspects e.g. how the intended learning outcomes are perceived in MR training, how the participants experience the learning in MR training, and what impact MR training will have in their future work practice.Method:An MR training system, designed for teams of up to four MFRs to perform training in real-time, will be pilot-tested at the beginning of 2023. The system features a fully functional touch-enabled human manikin design for practicing skills in emergency situations. The pilot tests will be carried out within the Med1stMR project (https://www.med1stmr.eu/) where approximately four teams of MFR will be evaluated based on the intended learning outcome.Results:Preliminary results from the pilot tests will be available at the conference.Conclusion:Research is needed to strengthen the knowledge and impact of MR training as a pedagogical method to better support MCI training and preparedness.