Premenstrual syndrome (PMS) and its more severe form, premenstrual dysphoric disorder, affect up to 18% of women. Both are commonly associated with other mood-related disorders such as major depression, and cause significant life impairment, but their relationship with personality disorders is less clear. After completing the Structured Clinical Interview for DSM-IV-TR disorders, 33 women with severe PMS and 26 asymptomatic women, counterbalanced for menstrual cycle phase, were administered the Structured Interview for DSM-IV Personality Disorders, a diagnostic interview with low transparency, strong inter-rater reliability, and good diagnostic clarity. Women with severe PMS had a higher prevalence of personality disorders (p = 0.003) than asymptomatic women (27% versus 0%), and were more likely to have odd-eccentric, dramatic-erratic, and anxious-fearful personality disorder traits (p < 0.05). Obsessive-compulsive personality disorder (OCPD) was the most common character pathology in the PMS group (n = 6, 18%). OCPD, although not necessarily associated with greater severity of premenstrual symptoms, was related to poorer life functioning in women with PMS. The comorbidity of a personality disorder and severe PMS places an additive burden on general life functioning and may have implications for psychiatric treatment or medication given to those with severe premenstrual symptoms.