Since the introduction of DSM-III Third Edition in 1980,there has been a growing interest in the study of patients with substance use disorders (SUD). The driving force behind this field has been, and still is, the high clinical pessimism about the prognosis, and the difficulties in the clinical management of the characteristics of diagnosed patients. Also religion and to be religious can play an important role in human’s individual and social life. The religion can be entered in many aspects of human behavior and can affect on their behavior and reduce probably of abnormal functions. So the study was aimed to investigate personality traits and religious orientation in two groups of addicted and nonaddicted people.

109 addicted people were randomly selected and compared with 109 nonaddicted people. Participants were asked to fill out Revised NEO Personality Inventory (NEO-FFM PI-R) and self-report questionnaire of Alport's E/I religious orientation. Mean scores were compared with T independent tests.

Analysis of means indicated significant differences among tow group. Compared to nonaddicted, addicted scored higher on Neuroticism, Openness to experience and External religious orientation, and lower on Extroversion, Agreeableness and Conscientiousness.

Based on results it is suggested that evaluating with reliable measures and with more attentions to intrinsic religious orientation related to personality traits can help the psychiatrists and psychologists to diagnose the cause of tendency to addiction and also reduce the psychological problems that is related with addiction before and in during drug treatment and can reduce duration of treatment and enhance efficacy of treatment methods.