Rejection sensitivity (RS) is defined as a cognitive-affective processing disposition of anxious expectation, ready perception and overreaction to rejection cues. RS is widely investigated in social psychology, but research on RS in clinical samples is scarce. Focus of the present study was to examine the role of RS in patients with borderline personality disorder (BPD) compared to other clinical disorders. The Rejection Sensitivity Questionnaire (RSQ) was adapted for application in clinical and non-clinical samples and proved to be a methodologically sound measure. High correlations between the RSQ and borderline-specific cognitions (Questionnaire of Thoughts and Feelings) were observed. Compared to several clinical samples as well as healthy controls, BPD patients indicated the highest scores on both measures and differed significantly from all other groups, even from patients with social anxiety disorders.