Background/Aims: To determine whether the Operationalized Psychodynamic Diagnosis (OPD) system can be useful in predicting patient outcome in the long term. Methods: OPD was assessed by the therapists prior to and after inpatient treatment. Patients completed psychometric scales at the start and completion of psychosomatic-psychotherapeutic inpatient treatment and at the follow-up. Outcome was defined by the general factor emerging from a principal component analysis of the Brief Symptom Inventory, Hospital Anxiety and Depression Scale and Inventory of Interpersonal Problems at katamnesis, representing individual differences in general distress. Results: Several dimensions of the OPD system proved to be predictors of general distress at the follow-up in 253 former inpatients. Negative predictors of long-term outcome were the high internal impediments to change, namely high secondary gains from illness and also less integrated structural abilities. Positive OPD predictors of long-term outcome were the treatment success achieved at the end of inpatient psychotherapy in changing the illness concept towards a psychological understanding of symptoms, lower levels of complaints and a higher functional level. Also the achieved level of awareness for the individual maladaptive behavioral pattern is predictive of a favorable long-term outcome. Conclusions: The results provide evidence for the clinical relevance and the predictive value of OPD.