Background The impact of delays in emergency department (ED) care has not been described in European countries where ED crowding is not universally recognized. The aim of this study was to determine the relationship of ED crowding with delays in triage and treatment, and 24-h mortality in patients admitted to the ED. Methods Five years of data from adults admitted to the hospital were analysed retrospectively from an inner-city ED in the Netherlands. Variables included the following: crowded versus noncrowded time, time to triage, triage category, time to treatment, age, 24-h mortality and 10-day mortality. Results A total of 39 110 patients met the inclusion criteria. ED crowding occurred 30.8% of the time. There were no differences in mortality between patients arriving during crowding versus those arriving during noncrowding. Delays in triage during ED crowding occurred 29.7% of the time versus 14.6% during noncrowding. Delays in treatment occurred 11.7 and 7.3% of the time during crowding and noncrowding, respectively. Conclusion In this hospital, ED crowding results in increased times to triage and to treatment, not in increased 24-h or 10-day mortality.@en