Two previous studies in Denmark found diverging results in analyzing trends in new cases of eating disorders in the psychiatric in- and day-patient services, although the same data source, the nationwide Danish Psychiatric Case Register, was used. The present study--also using information from the nationwide Danish Psychiatric Case Register, but correcting for several register biases--confirms a highly significant increase in new cases of eating disorders in psychiatric hospitals and wards. The increase is seen exclusively in younger females. The diverging results in the previously mentioned studies in Denmark may be ascribed to methodological issues.