Contemporary medical approaches for opioid addiction often include medication-assisted therapy, utilizing methadone and buprenorphine. However, factors influencing patient preferences for starting buprenorphine or methadone therapy are poorly understood. This study aims to explore whether variances in personality traits and attachment styles are related to treatment preferences among individuals undergoing buprenorphine and methadone maintenance therapies. 300 participants completed the Big Five Questionnaire for personality traits and sub-dimensions and the Experiences in Close Relationship Scale for assessing attachment styles. The results indicated that patients with higher levels of Dynamism, Conscientiousness, and Perseverance personality traits were more likely to choose buprenorphine over methadone for achieving and maintaining abstinence. Although attachment styles showed a greater ability to differentiate between groups compared to personality traits, the differences were not significant. However, Conscientiousness stood out for its high discriminant validity, suggesting that scores in this personality dimension could significantly distinguish between groups, with individuals in the buprenorphine group showing higher levels of Conscientiousness compared to the methadone group. The study suggests a partial association between individuals' preference for abstinence therapy and their personality traits. These findings could be considered useful indicators when choosing maintenance therapy to help opiate-addicted patients achieve and maintain abstinence.Contemporary medical approaches for opioid addiction often include medication-assisted therapy, utilizing methadone and buprenorphine. However, factors influencing patient preferences for starting buprenorphine or methadone therapy are poorly understood. This study aims to explore whether variances in personality traits and attachment styles are related to treatment preferences among individuals undergoing buprenorphine and methadone maintenance therapies. 300 participants completed the Big Five Questionnaire for personality traits and sub-dimensions and the Experiences in Close Relationship Scale for assessing attachment styles. The results indicated that patients with higher levels of Dynamism, Conscientiousness, and Perseverance personality traits were more likely to choose buprenorphine over methadone for achieving and maintaining abstinence. Although attachment styles showed a greater ability to differentiate between groups compared to personality traits, the differences were not significant. However, Conscientiousness stood out for its high discriminant validity, suggesting that scores in this personality dimension could significantly distinguish between groups, with individuals in the buprenorphine group showing higher levels of Conscientiousness compared to the methadone group. The study suggests a partial association between individuals' preference for abstinence therapy and their personality traits. These findings could be considered useful indicators when choosing maintenance therapy to help opiate-addicted patients achieve and maintain abstinence.