The purpose of this study was comparing the clinical personality patterns and severe personality disorders in patients with HIV infection and normal individuals. The sample was consisted of 100 subjects (50 patients with HIV infection, 50 normal individuals) that were selected through available population. Subjects completed the Millon Clinical Multiaxial Inventory II (MCMI-II) and researcher-made questionnaire number 1 (pertaining to patients that affected to HIV infection due to implicated syring) and researcher-made questionnaire number 2 (pertaining to patients that have been infected to HIV infection due to unprotective sexual relationships). The MANOVA results indicated that there are meaningful differences in some clinical personality patterns (such as schizoid, avoidant, antisocial, aggressive, obsessive, passive- aggressive and self-defianting) and severe personality disorders (such as schizotypal and borderline) between research groups. Furthermore, the patients with HIV infection reported high rate of high- risk behaviors, background in prison, history of alcohol using and the cup history. On the base of findings of current research can concluded that certain personality patterns, particularly antisocial and borderline patterns increase vulnerability to HIV infection. Also the precise assessment of the personality disorders is essential to more effective prevention and treatment of patients with HIV infection.