Borderline personality disorder (BPD) is characterized by instability of interpersonal relationships and affection, impulsivity, and cognitive disruptions. Increasing evidence suggests hypothalamic-pituitary-adrenal (HPA) axis alterations in BPD. Changed glucocorticoid sensitivity of peripheral blood mononuclear cells is known in mood and posttraumatic stress disorders, representing frequent comorbidities in BPD. However, to the authors' knowledge, in BPD glucocorticoid sensitivity at the receptor level remains unexplored. Sixteen age-matched female BPD patients were compared to sixteen female healthy controls. In vitro steroid sensitivity of T cell proliferation was tested using aldosterone, dexamethasone, and hydrocortisone. Steroid sensitivity of BPD patients and healthy controls appeared comparable. Psychiatric comorbidities such as major depressive disorder or posttraumatic stress disorder and early life stress seemed to have had no influence on steroid sensitivity parameters. The data suggest unaltered GC sensitivity of T cell function in BPD.