<h3>Aim</h3> Demographic changes, decreasing availability of general practitioners, and at least regional shortage of qualified emergency medical service (EMS) physicians led to increasing arrival times and quality problems. Telemedical solutions could help to solve some of the problems. <h3>Methods</h3> Overall safety and feasibility of prehospital telemedically guided care was already proven in two research projects from 2007 to 2013.<sup>1–3</sup> Their results led to implementation of a multifunctional mobile telemedicine system in the city of Aachen, Germany. From 04/2014 to 03/2015 all ambulances were equipped with a telemedicine system connected to a teleconsultation centre staffed with anesthesiologists experienced in emergency care. Audio, real-time vital data, 12-lead-ECG, picture transmission, and video streaming from ambulances was accomplished with encrypted and parallelized transmission using. Mission numbers prior and after implementation were compared to evaluate systematic influence. <h3>Results</h3> From 04/2014 to 06/2016 overall 4.901 EMS missions were supported and guided telemedically: n=4.151 emergency missions (85%) and n=750 (15%) inter-hospital transfers. Prior to implementation (04/2013–03/2014) 17.305 solely ambulance missions (68.7%) and 7.882 ambulance plus EMS physician unit missions were performed (31.3%). After implementation (04/2015–03/2016) 20.102 ambulance missions (76%) and 6.360 ambulance plus EMS physician missions (24%) were conducted which revealed a significant difference between both phases, p<0.0001. <h3>Conclusion</h3> The implementation of a telemedicine system into routine care led to a significant decrease in conventional on-scene physician missions as well as to an overall decrease in physician guided EMS cases. Therefore, the approach can be judged resource optimising and holds a potential for economic improvements although highly qualified physicians carry out the service. <h3>References</h3> Brokmann JC, Conrad C, Rossaint R, Bergrath S, Beckers SK, Tamm M, Czaplik M, Hirsch F. Treatment of acute coronary syndrome by telemedically supported paramedics compared with physician-based treatment of acute coronary syndrome: a prospective, interventional, multicentre trial. J Med Internet Res2016;18(12):e314doi:10.2196/jmir.6358 Felzen F, Brokmann JC, Beckers SK, Hirsch H, Tamm M, Rossaint R, Bergrath S. Technical performance of a multifunctional prehospital telemedicine system in routine emergency medical care – an observational study. Journal of Telemedicine and Telecare2016; pii: 1357633X16644115. Bergrath S, Reich A, Rossaint R, Rörtgen R, Gerber J, Fischermann H, Beckers SK, Brokmann JC, Schulz JB, Leber C, Fitzner C, Skorning M. Feasibility of Prehospital Teleconsultation in Acute Stroke – a pilot study in clinical routine. PLoS ONE2012;7(5):e36796. <h3>Conflict of interest</h3> None declared. <h3>Funding</h3> None declared.