Personality disorders are considered as inflexible and incompatible styles in relation to the environment. Individuals with these types of disorders, in spite of their warmth and friendly look , are prone to commit illegal and criminal activities. Therefore, the present study aims to investigate the status of personality disorders in prisoners. To this end, 182 male prisoners confined in Lorestan Central Prison, were randomly selected and evaluated using Milon 3 (MCMI-111) questionnaire. Then, data gathered from Milon 3 questionnaire was evaluated in Milon 3 application in order to determine the Br score. To analyze the data, One-way ANOVA and Independent –Samples t-test were applied. The findings indicated that there was a statistically significant difference between individuals with different crimes in drug addiction personality with 99% confidence, antisocial personality disorder and Sadistic personality with 95% confidence level. The findings also showed that antisocial personality disorder, drug addiction and avoidant personality disorder were mostly found in thieves. Moreover, in comparing personality disorders among individuals with different incarceration rates, only depression personality disorder in the studied groups was found to be statistically significant with 95% confidence level. Furthermore, the results of the Independent –Samples t-test which compared personality disorders in single and married individuals showed that Sadistic personality disorders and depression, with 95% confidence level, were more significant in single than married prisoners.