Background: Schema Therapy (ST), a psychotherapy model integrating cognitive, experiential and behavioural interventions, was initially developed and evaluated as an outpatient treatment for patients with severe and chronic disorders, among them Borderline Personality Disorder (BPD). Two randomized controlled trials have demonstrated the effectiveness of ST for BPD, delivered in an individual or group format, in the outpatient setting. However, the most severely impaired BPD patients are referred to inpatient treatment due to suicidality and severe self-harm. Specialized inpatient treatment programs are limited, with little evaluative research. Aims: The pilot studies are designed to be first steps in naturalistic clinical settings to evaluate the effects of an intensive inpatient ST treatment program. Method: This report presents the results of three independent uncontrolled pilot studies with a total of 92 BPD patients. The programs combine individual and group modalities and are consistent theoretically with the ST model for BPD patients. Results: Results show that inpatient ST can significantly reduce symptoms of severe BPD and global severity of psychopathology with effect sizes ranging from Cohen's d = 2.84 to Cohen's d = .43. Conclusions: Differences in the effect sizes across the three pilot studies could be explained by length of treatment, number of group psychotherapists and their training. Although there are limitations to the presented pilot studies such as differences in the samples, treatment settings, variations in the treatment itself and the use of different measures, which may have influenced outcome, they are a starting point for describing and evaluating inpatient treatment for BPD in naturalistic settings.