Objective: The aim of this study was to compare personality traits based on the temperament and character inventory (TCI) in opiate and stimulant users of Yasuj.

Materials & Methods: In this descriptive –comparative study, 115 persons (91 opiate substance users and 24 stimulant substance users) were selected by simple and convenient sampling from persons who were admitted to substance abuse treatment centers (MMT centers), addiction treatment camps and self-help groups and Narcotics Anonymous (NA) of Yasuj. Subjects were controlled for age. The data collection tool was the ‘Temperament and Character Inventory’ (TCI). Data were analyzed by SPSS using Levene’s test, ANOVA and Pearson’s correlation coefficient.

Results: The findings showed significant differences in Novelty seeking, Harm avoidance, Persistence, Cooperativeness, Self-directiveness, and Self-transcendence between opiate and stimulant users. In all the abovementioned subscales the mean values of stimulants were higher than opiates. There were no significant differences in subscales of personality traits based on age.

Conclusion: Based on the mean values of the TCI, personality traits reflecting personality disorders are detectable and predictable in substance abusers. This is important in the prevention and treatment of addiction.