Background :Co-morbid psychiatric disorders affect prognosis, psychosocial adjustment and post-surgery satisfaction in patients with gender identity disorder. In this paper, we assessed the frequency of personality disorders in Iranian GID patients.

  Methods : Seventy- three patients requesting sex reassignment surgery (SRS) were recruited for this cross- sectional study. Of the participants, 57.5% were biologically male and 42.5% were biologically female. They were assessed through the Millon Clinical Multiaxial Inventory II (MCMI- II).

  Results : The frequency of personality disorders was 81.4%. The most frequent personality disorder was narcissistic personality disorder (57.1%) and the least was borderline personality disorder. The average number of diagnoses was 3.00 per patient.

  Conclusion : The findings of this study revealed that the prevalence of personality disorders was higher among the participants, and the most frequent personality disorder was narcissistic personality disorder (57.1%), and borderline personality disorder was less common among the studied patients.