en پژوهشي Original Research Articles <p style="text-align: justify;"><strong>Objectives:</strong> According to the gateway drug theory, tobacco use is a predisposing factor for future substance abuse. This study was conducted to compare nicotine and opiate dependents to identify the differences between their personality traits and psychopathology that makes them turn to other substances after cigarette smoking.</p> <p style="text-align: justify;"><strong>Methods:</strong> A causal-comparative study was conducted. Three groups were randomly selected: nicotine dependents, opiate dependents and ordinary individuals (non-dependent population). Cloninger&rsquo;s Temperament and Character Inventory-Revised, the Fagerstrom Test for Nicotine Dependence, Maudsley Addiction Profile, the Beck Depression Inventory, and Beck Anxiety Inventory were used to collect data. Analysis of variance was used to analyze data.</p> <p style="text-align: justify;"><strong>Results:</strong> Opiate dependents had higher &lsquo;novelty seeking&rsquo; and lower &lsquo;cooperativeness&rsquo; scores as compared to the other two groups. They also had higher anxiety and depression scores than the other two groups.</p> <p style="text-align: justify;"><strong>Discussion:</strong> Higher &lsquo;novelty seeking&rsquo; and lower &lsquo;cooperativeness&rsquo; scores are important personality traits predicting</p> Opiate substances, Nicotine, Temperament, Character 60 56 http://irj.uswr.ac.ir/browse.php?a_code=A-10-348-3&slc_lang=en&sid=1 Bahareh Amirabadi dostian2438@yahoo.com No Shahid Beheshti University of Medical Sciences, Tehran, Iran. Neda Alibeigi nedapsych@gmail.com No University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. Mohammad Nikbakht om.massah@uswr.ac.ir No Shahid Beheshti University of Medical Sciences, Tehran, Iran. Omid Massah omchomch@gmail.com No Substance Abuse and Dependence Research Center, University of Social Welfare & Rehabilitation Sciences, Tehran, Iran. Ali Farhoudian farhoudian@yahoo.com Yes Substance Abuse and Dependence Research Center, University of Social Welfare & Rehabilitation Sciences, Tehran, Iran. Younes Doostian dostian2438@gmail.com No University of Social Welfare & Rehabilitation Sciences, Tehran, Iran.