This study examines the relationship of personality disorders (PDs) with the outcome of an inpatient treatment for depression. One hundred sixty-eight inpatients with unipolar depression (41% with PD according to SCID-II) were assessed at admission, discharge, and 1-year follow-up. Patients without as well as with PD showed a significant and comparable intake-to-discharge symptom reduction in all inventories. At posttreatment, patients with PD scored higher in self-report measures of symptom severity (Brief Symptom Inventory, Beck Depression Inventory) than patients without PD, due to their higher symptom levels at intake. However, there was no difference in clinician-rated therapy outcome (Hamilton Rating Scale for Depression [17-item version], Global Assessment of Functioning Scale, Clinical Global Impression Scale) between both patient groups at discharge. At 1-year follow-up, patients without PD maintained their treatment outcome, whereas patients with PD showed a slight increase in symptom severity, compared to discharge. The results suggest that a difference in acute treatment outcome between depressed patients with and without PD may be found using self-ratings but not expert ratings of symptom severity. Furthermore, the importance of subsequent outpatient treatment that takes into account the special needs of depressed patients with comorbid PD is highlighted.