Aim of the study: Poor safety culture, bad teamwork, non-functional inter-departmental working relationships and increased cognitive demands are associated with higher amounts of adverse events in hospitals. To improve patient safety, one of the first steps is to assess safety culture among health care providers in an institution. Considering the sparsity of studies addressing patient safety culture in Europe and Switzerland, the aim of the present study was to assess patient safety culture in the emergency department of a University Hospital in Switzerland. Methods: We employed the Hospital Survey On Patient Safety Culture, developed by the U.S. Agency for Healthcare Research and Quality. 140 questionnaires were distributed to nurses and physicians. Two weeks after the first questionnaire, we performed a sensitization campaign addressed to health care providers, and then repeated the survey. We calculated composite scores for each question category and percentages of positive responses for each dimension. For group comparisons such as possible differences relating to education and duration of employment and to compare results of the first and second survey we used T-tests. The results were compared to other published surveys outside of Switzerland. Results: Particularly positive assessments were found for the categories "nonpunitive response to errors", "teamwork within units", "supervisor/manager expectations and actions promoting patient safety" and, compared to other hospitals, also "staffing". The lowest average percent positive responses were found in the categories "frequencies of reported event", "teamwork across units" and "handoffs and transitions". Nurses and health care personnel with a longer employment history had an overall more negative assessment of patient safety culture, when compared to physicians and personnel with a shorter duration of employment, respectively. Conclusions: The present study has identified strengths and potential weaknesses in the safety culture of a large university hospital emergency department in Switzerland. The results provide opportunities for improvement of patient safety in particular in the reporting of adverse events, in interaction across units and patient transitions. Furthermore, as we employed a standardized self-assessment tool similar to previously published studies, the work contributes to the establishment of a benchmark for hospital safety culture at the national, European and international level.