en Original/Research Article <div style="text-align: justify;"><strong>Introduction:</strong> Breast cancer is one of the most common cancers among women and is the second leading cause of death among them. Breast cancer can often make people prone to psychological problems and reduce their self-efficacy and quality of life. The purpose of this research was to study the effectiveness of cognitive behavior therapy on self-efficacy and quality of life of women with breast cancer.</div> <div style="text-align: justify;"><strong>Materials and Methods: </strong>The study was a quasi-experimental study. The sample included 32 women in the third stage of breast cancer in cancer part of Emam Khomeyni hospital located in Tehran, Iran. They were matched for age, duration of disease and other criterias. The subjects randomly divided into two groups as experimental and control group (n = 16 for each). For experimental group, we used 8 sessions of 2hours of cognitive behavior therapy, but the control group did not receive any intervention. The measurement tools were the Sherer self-efficacy questionnaire and the quality of life questionnaire. Multivariate analysis of covariance was used to analyze the data.</div> <div style="text-align: justify;"><strong>Results:</strong> Data showed that there was a significant difference between pre-test and posttest experimental and control groups in terms in self-efficacy and quality of life scores (P<0.001).</div> <div style="text-align: justify;"><strong>Conclusions: </strong>This study showed that cognitive-behavioral group therapy effect self-efficacy and quality of life in women with breast cancer.</div> Breast Cancer, Self-Efficacy, Quality of Life, Cognitive Behavior Therapy 0 0 http://mcijournal.com/browse.php?a_code=A-10-33-79&slc_lang=en&sid=1 Khadijeh Babakhani 1003194753284600864 1003194753284600864 Yes