All calls prospectively registered by the Augsburg Rescue Co-ordination Centre (ARCC) in the 5 years from July 1997 to June 2002 were analysed, distinguishing between the different types of damage, number of patients involved, and time of occurrence (time of day/season). The area served by the ARCC includes the city of Augsburg with its surrounding counties. An estimated 850,000 inhabitants live in this area of 4,100 square kilometers (1,600 square miles). Since 1998, more than 145,000 calls a year have been dealt with of which 28,000 were covered by emergency physicians. In the 5 year period discussed here, 75 large-scale-calls were registered, giving an average incidence of 1.25 calls/month. Most of the calls were fire alarms, followed by car accidents. In total, we were able to serve more than 800 patients. The lowest number per event was two people during an emergency landing of a sport aircraft; the largest number was about 150 patients during a large open-air event in the city. While there was no difference in the time of day at which the event happened, most occurred in November and December. Taking these results into account, the authors, supported by the members of the emergency physician team of the German Trauma Society, developed an algorithm describing the optimal procedure for mass casualty events. This is presented here. In mass casualty or large-scale emergency events, an experienced emergency physician is necessary to co-ordinate the rescue brigades on site.