Background: Dropout from psychotherapy is an important problem that has received little systematic attention. Although previous research suggests that the number of patients who drop out is considerable, it is not clear why they drop out or what might be done to limit the problem. The present study attempted to examine the role of the patient-therapist relationship as well as other variables for dropout among eating disorder patients. Methods: Eating disorder patients and their therapists were assessed on a measure of treatment expectations previously developed by the author: the former were also assessed on measures of psychiatric symptoms (Crown-Crisp Experiential Index) and eating disorder psychopathology (Eating Disorder Inventory), as well as relevant background and treatment variables. Patients were divided into those who had completed their course of treatment, and those who dropped out during assessment or treatment. Results: Lack of congruence between patients’ and therapists’ expectations of potential treatment interventions was associated with increased risk of dropout, whereas other patient-, therapist-and treatment-specific factors were not. In particular, dropouts had significantly greater expectations of being helped by insight-related interventions than their therapists. Conclusions: Dropout among eating disorder patients appears to be related to the patient-therapist relationship. It may be important for therapists to openly discuss patient expectations of treatment from the outset, and focus on particular areas of discrepancy to limit potential dropout.