Objective: The aim of this study is to investigate the factors which affect the mindfulness and trying to determine the role of mindfulness on addiction. In this regard, the aim is to review the use of practicing mindfulness based therapies in the treatment. Methods: One hundred ninety one patients who have been taking treatment in Alcohol and Substance Addiction/Abuse Research and Treatment Center were included in the substance users group. A total of one hundred people, comprised of seventy five teachers and twenty five bank clerks, were included in the non-users group. Mindful Attention Awareness Scale (MAAS), General Health Questionnaire (GHQ), White Bear Suppression Inventory (WBSI), Meta-cognitions questionnaire (MCQ-30), The Emotion Regulation Questionnaire (ERQ), MMPI Impulsivity Scale (IMP), SCID-I, Structured Clinical Interview for DSM-IV Axis I Disorders were administered to the participants. Results: There were no significant differences of mindfulness levels between the addicted and non-addicted groups. When two groups were compared, statistically significant differences of IMP, WBSI, MCQ-30, ERQ suppression subscale and GHQ levels were observed. Lower levels of mindfulness were observed on users who did not receive any treatment in the past and users of non-alcoholic substances. Conclusion: In light of the results of this study, it was determined that albeit the significant differences between the levels of factors which are known to affect mindfulness, including metacognition, repression, impulsivity and physical problems, between groups, there was insignificant difference of mindfulness level observed in both the addicted and non-addicted groups, and this observation was deemed a trace of MAAS scale failing to properly measure the Mindfulness level. The significantly different levels of factors which affect the mindfulness observed in the addicted group indicate that the Mindfulness therapy might be beneficial in addiction.