Abstract Background Emergency departments (ED) recognize crowding and handover from prehospital to in-hospital settings to be major challenges. Prehospital Geographical Information Systems (GIS) may be a promising tool to address such issues. In this study, the use of prehospital GIS data was implemented in an ED in order to investigate its effect on 1) wait time and unprepared activations of Trauma Teams (TT) and Medical Emergency Teams (MET) and 2) nurses’ perceptions regarding patient reception, workflow and resource utilization. Methods Intervention: From May 1st 2014 to October 31th 2014, GIS data was displayed in the ED. Data included real-time estimated time of arrival, distance to ED, dispatch criteria, patient data and ambulance contact information. Data was used by coordinating nurses for time activation of TT and MET involved in the initial treatment of severely-injured or critically-ill patients. In addition, it was used as a logistics tool for handling all other patients transported by ambulance to the ED. Study design: The study followed a mixed-methods design, consisting of a quantitative study (before and after intervention) and a qualitative study (survey and interviews). Participants: Participants included all patients received by TT or MET and coordinating nurses in the ED. Results 1.) Quantitative: 599 patients were included. The median wait time for TT and MET was 5 min both before and after the GIS intervention, showing no difference (p = 0.18). A significant reduction in the subgroup of waits >10 min was found (p 10 minutes may have contributed to the overall perception of reduced wait time, as avoidance of long waits is clinically more important than reduction in the median wait time. Conclusion A comparison of the use of prehospital GIS data in the ED with the control period showed no effect on median wait time for TT and MET, however, the number of waits of >10 min was reduced. On the other hand, nurses perceived implementation of GIS data as improving workflow, resource utilization and quality of all patients’ reception, critically as well as non-critically ill. There were no substantial disadvantages to the GIS application. Trial registration ClinicalTrials.gov ( NCT02188966 ).