BACKGROUND: In 2003, the German psychiatrist Michael Linden proposed the new mental disorder concept of "post-traumatic embitterment disorder (PTED)". PTED is defined as the mental reaction to a critical event that is normal, but not everyday, such as conflict at work. The patient sees this event as unjust and as a violation of basic beliefs. The principal aspect of the reaction pattern is a prolonged feeling of embitterment. AIM: In the present paper, the concept of PTED is systematically evaluated. Moreover, future developments in terms of diagnostic systems of mental disorders (ICD-11, DSM-V) are addressed. RESULTS: The evaluation of critical points concerning PTED revealed that the question of whether PTED is a mental disorder of the post-traumatic type cannot be finally answered. It is not possible to specify an empirical criterion by means of which traumatic and non-traumatic life events can be differentiated. An empirical criterion for determining the traumatic nature of a given event depends on whether this event has already been classified as traumatic (i.e. circular argument). CONCLUSIONS: For the purpose of a clear classification of embitterment disorders, the new concept of adjustment disorders of Andreas Maercker and co-workers is introduced. Based on the criteria and their findings, the best and most viable possibility to classify embitterment disorders in accordance with the current adjustment disorder and post-traumatic stress disorder definitions of ICD and DSM is by regarding embitterment disorders as a subtype of adjustment disorders.