Despite evidence of a relation between borderline personality disorder (BPD) pathology and physical health problems, the mechanisms underlying this relation remain unclear. Given evidence that emotion dysregulation may affect physical health by altering physiological functioning, one mechanism that warrants examination is emotion dysregulation. This study examined BPD symptoms as a prospective predictor of physical health symptoms 8 months later and the mediating role of emotion dysregulation in this relation. Participants completed three assessments over an 8-month period, including a BPD diagnostic interview. Results of analyses examining baseline predictors of later physical health symptoms revealed a significant unique association between baseline BPD symptom severity and physical health symptoms 8 months later, above and beyond baseline physical health symptoms, depression and anxiety symptoms, and emotion dysregulation. Moreover, structural equation modeling revealed a significant indirect relation of BPD symptoms at Wave 1 to physical health symptoms at Wave 3 through emotion dysregulation at Wave 2.