Introduction. Medical preparedness at mass gatherings is challenging, as little is known about the optimal planning. Most studies and case reports are based on mass casualty incidents, so the results cannot be extrapolated to mass gatherings. Aim of this study was to evaluate the preclinical medical structure and the frequency of specific injuries and medical emergencies during the event. Methods. Retrospective analysis of a prospectively collected database. Three on-site medical assistance points were set up, completed by mobile teams, and coordinated by an on-site operational management team. Medical staff requirements were calculated using Maurer's formula. Results. A total of 1,533 patients were treated during the three-day event. Overall, the medical usage rate (MUR; patients per 10,000 visitors) was 51.1. A total of 58 patients (3.8%) required a hospital transfer. In 1,063 cases (69.3%) a diagnosis was documented. Of these, 503 patients (47.3%) suffered from hymenoptera stings; the two most common non-trauma-related diagnoses were alcohol/drug intoxication (4.1%) and gastrointestinal diseases (4.0%). Conclusion. Overall, the on-site medical care worked well. However, a high frequency of hymenoptera stings occurred, resulting in a shortage of antihistamine medication. Moreover, more than half of the patients were managed at the second largest medical assistance point. Prospective and critical evaluation of medical care at mass gatherings is crucial in order to optimize on-site medical preparedness at future events.