Background and Aim The purpose of this study was to evaluate the relationship between stress coping strategies and difficulties in emotion regulation mediated by marital life quality in married women with breast cancer. Methods & Materials This is a descriptive correlational study. The study population included all married women with breast cancer in Amol and Babol cities of Iran in 2018. Of these, 385 were selected through a convenience sampling technique. The research instruments were Ways Of Coping Questionnaire, Difficulties In Emotion Regulation Scale and Marital Life Quality Scale. The goodness-of-fit of proposed model was examined by Structural Equation Modeling (SEM) in LISREL software. The indirect correlations were tested by using Preacher and Hayes' bootstrapping method. Ethical Considerations This study received its ethical approval from Islamic Azad University of Tonekabon Branch (Code: IR.IAU.TON.REC.1397.029). Informed consent was obtained from all participants. Results The proposed model had good fit (RMSEA=0.057). All direct correlations were reported significant (P<0.05). Moreover, indirect paths between stress coping strategies and difficulties in emotion regulation through mediation by marital life quality were significant. Conclusion The proposed model had a good fit and can be used in identifying the factors affecting difficulties in emotion regulation. It can be useful for designing and developing programs to prevent emotions problems in women with breast cancer.