['The objective of this article was to qualify and test the recommendations of a national Danish report. We conducted an investigation on the readmittance rate as well as reasons for readmittance in a patient cohort defined through the process of internal audit at the Emergency Department at Zealand University Hospital, Køge, Denmark.', 'A retrospective, descriptive study of admitted patients in November 2014, including a total of 1,440 patients. Data and parameters were obtained from electronic patient records.', 'A total of 162 patients were readmitted within 30 days from their initial admission (11% of the cohort). Of this group, 139 (86%) readmittances were unpreventable or planned. Readmissions caused by missed diagnosis or insufficient treatment accounted for 8% and 6%, respectively. The median time until readmission in these cases were two and four and a half days, respectively. The median time to readmission for the unpreventable readmissions ranged from 13 to 18.5 days.'] Are readmittance rates within seven days preferable in quality measuring of emergency departments?