en Clinical Psychology پژوهشي Research Article <span style="font-size:12px;"><span style="font-family:Tahoma;"><span style="line-height:normal"><span style="unicode-bidi:embed"><b><span style="color:black">Background and Objective:</span></b> This study aimed to compare the effectiveness of cognitive-behavioral therapy and acceptance and commitment therapy on psychological hardiness in patients with leukemia.</span></span><br> <span style="line-height:normal"><span style="unicode-bidi:embed"><b><span style="color:black">Materials and Methods:</span></b> The research method followed a semi-experimental, pre-test-post-test design with a control group and a follow-up stage. The statistical population of the study included all patients with chronic lymphocytic and myeloid leukemia who visited the Chemotherapy Clinic of Rajaei Hospital, Karaj, Dr. Asadi Oncology Clinic, and Karaj&rsquo;s Mehr Soheila Cancer Charity Institute, in 2024. From which, 45 participants were selected by purposive sampling and randomly assigned to three groups, namely, cognitive-behavioral therapy, acceptance and commitment therapy, and the control group. Participants answered a psychological hardiness questionnaire for pre-test, post-test, and follow-up stages. Therapeutic interventions included 10 sessions of cognitive-behavioral therapy protocol and eight sessions of acceptance and commitment therapy protocol, implemented as group activities. Data were analyzed using mixed analysis of variance.</span></span><br> <span style="line-height:normal"><span style="unicode-bidi:embed"><b><span style="color:black"><span style="letter-spacing:.1pt">Results:</span></span></b> The findings showed that, compared with the control group, both therapeutic interventions improved patients&#39; psychological hardiness at the post-test phase, and this effect was maintained at the follow-up stage.</span></span><br> <span style="line-height:normal"><span style="unicode-bidi:embed"><b><span style="color:black">Conclusions:</span></b> Based on the findings obtained, both cognitive-behavioral therapy and acceptance and commitment therapy are effective interventions for improving the psychological well-being of patients&#39; with leukemia.</span></span></span></span><br> &nbsp; Acceptance and Commitment Therapy, Cognitive-Behavioral Therapy, Leukemia, Psychological Hardiness 201 207 http://ajnpp.umsha.ac.ir/browse.php?a_code=A-10-2447-1&slc_lang=en&sid=1 Fereydoon Bagheri Khatoonabadi fereydoon.bagherikhatoon@gmail.com 10031947532846008841 0009-0003-8835-9754 No Department of Health and Clinical Psychology, Ka. C., Islamic Azad University, Karaj, Iran Farahnaz Meschi farahnaz@iau.ac.ir 10031947532846008842 10031947532846008842 Yes Department of Health and Clinical Psychology, Ka. C., Islamic Azad University, Karaj, Iran Mona Darya Afzoon m.daryaafzoon@iau.ac.ir 10031947532846008843 10031947532846008843 No Department of Health and Clinical Psychology, Ka. C., Islamic Azad University, Karaj, Iran Alireza Shokrgozar dralirezashokrgozar@iau.ac.ir 10031947532846008844 10031947532846008844 No Department of Health and Clinical Psychology, Ka. C., Islamic Azad University, Karaj, Iran Fatemeh Mohammadi Shirmahaleh fatemeh 2020@iau.ac.ir 10031947532846008845 10031947532846008845 No Department of Health and Clinical Psychology, Ka. C., Islamic Azad University, Karaj, Iran