Background: The term ‘posttraumatic embitterment disorder’ (PTED) was recently introduced to describe a subtype of adjustment disorders, characterized by prolonged embitterment, severe additional psychopathological symptoms and great impairment in most areas of life in reaction to a severe negative but not life threatening life event. The aim of this study is an empirical description and validation of the clinical concept of PTED, by comparing clinically defined PTED patients with patients suffering from other mental disorders on measures of posttraumatic stress and psychopathological distress. Methods: Fifty inpatients, suffering from PTED according to previously defined clinical diagnostic criteria, were compared with another 50 patients, matched by age and gender, who did not meet clinical criteria for PTED but for other mental disorders. Psychiatric diagnoses were assessed by the Mini International Neuropsychiatric Interview. Self-report measures included the Bern Embitterment Scale, the Impact of Event Scale, the PTED Self-Rating Scale and the SCL-90. Results: According to the Mini International Neuropsychiatric Interview both groups fulfilled the criteria for many disorders with a significantly higher occurrence of major depression and chronic adjustment disorder but less generalized anxiety disorder lifetime in PTED patients. Patients with PTED scored significantly higher on the global scores and on most subdimensions of the SCL-90, the Impact of Event Scale, the Bern Embitterment Scale and the PTED Self-Rating Scale. Conclusions: Clear differences were found between PTED patients and patients with other mental disorders in regard to the quality and intensity of psychopathological as well as posttraumatic stress symptoms. PTED can help further subclassify and specify adjustment and reactive disorders.