The target of current research was to determine the effectiveness of group psychotherapy based on acceptance and commitment on increasing of mental health and the quality of patients, life with breast cancer, For this purpose, in a semi trial research 30 persons of women with breast cancer in Omid hospital of Urmia city were selected with available sampling method and they were randomly divided into two trial (15 persons) and control (15 persons) groups. Test group received an interference based on acceptance and commitment in 8 sessions (each session 90 minutes), but no interference was accomplished on control group. Both groups were tested in two pre-test and post-test stages by questionnaire of Quality Of Lifefor patients with breast cancer (QOL_BR23) and Goldberg mental Health Questionnaire of Goldberg (GHQ). The results of covariance analysis showed that therapeutic plan could improve all aspects of mental health of test group subjects and two aspects of social health and physical health of life quality but it couldn’t influence on conditions of subjects in two aspects of psychological health and environmental health of interference. Therefore we can express that group psychotherapy based on acceptance and commitment can be effective on promotion of mental health and quality of patients, life with breast cancer.