Background: The onset of the COVID-19 pandemic was characterized by rapidly increasing patient volumes, which necessitated a swift emergency department (ED) overhaul. Challenges mainly concerned surge capacity, frontline staff protection and the segregation of patients with suspected COVID-19. To date, only few studies have assessed nation-wide ED preparedness for the COVID-19 pandemic. This study aimed to form an overview of preparations that were taken in Dutch EDs during the initial phase of this public health crisis. Methods: This study was designed as a nation-wide, cross-sectional, questionnaire-based study among Dutch hospital organizations with an ED. The questionnaire was conducted between the first and the second wave of the COVID-19 pandemic in the Netherlands and contained close-ended and open-ended questions on changes in ED infrastructure, ED workforce adaptions and the role of emergency physicians (EPs) in the hospital crisis organizations. Results: Overall response rate was 79.5%. All EDs had made preparations in anticipation of a possible COVID-19 surge. Treatment capacity was expanded in 69.7% of EDs, with a median increase of 49% (IQR 32.5-72.7%). COVID-19 suspected patients were segregated from non-COVID-19 patients in 86.4% of EDs. Non-COVID-19 patients were more often assessed at alternative locations than patients with suspected COVID-19 infection. In 81.8% of EDs the workforce was expanded, which mainly concerned expansion of nursing staff. A formal role of EPs in the hospital crisis organizations was reported by 93.9% of EP staffed hospital organizations. Conclusion: All Dutch EDs made preparations for COVID-19 in a short time span and with many uncertainties. Preparations predominantly concerned expansion of treatment capacity and segregation of COVID-19 ED care. EPs had a prominent role, both in direct patient COVID-19 ED care and in the hospital crisis organizations. Although it is vital for EDs to be able to dynamically adapt to community needs, variability of pandemic ED preparedness was high.