Objectives : The present study was conducted as a part of a broader study on gender roles in patients with gender identity disorder (GID), and its goal was to determine patients’ sexual orientation comparing to healthy controls. Method: In current cross-sectional study, 12 males and 27 females with GID were compared with 81 male and 89 female controls. The participants’ gender orientation and gender self-identity were investigated via asking two questions. Data analysis was carried out using t-test, analysis of variance, chi-square, and kappa statistic. Results: In the male-to-female GID patients, one participant was sexually attracted to females and the rest (91.7 percent) to males. In the female-to-male GID patients, the frequency of sexual orientation to females and males were 96.3 percent and 3.7 percent, respectively. The frequency of heterosexuality in male and female controls was 93.8 percent and 69.7 percent, respectively. The frequency of individuals with GID who sexually attracted to the same-sex showed no statistically significant difference between males and females (p>0.05), though a substantial concordance was observed between these patients’ biological sex and sexual orientations (κ=0.653, SE=0.164, p<0.001). Conclusion : In Iranian patients with GID, a substantial concordance was observed between biological sex and sexual orientation .