Background: The Mini-Mental Adjustment to Cancer Scale (Mini-MAC) instrument is commonly used worldwide by professionals of oncology, but the scale has not, up to date, been validated in Arabic and Moroccan context, and there is absence of data in the Moroccan population. This study aims to validate the Mini-MAC, translated and adapted to the Arabic language and Moroccan culture, in women with breast cancer.Methods: The Mini-MAC instrument was administered to 203 breast cancer women, receiving medical care in the university Hospital of Fez city. A cross-sectional validation study using exploratory factor analysis and Confirmatory factor analysis was carried out.Results: Confirmatory factor analysis confirmed Watson’s original structure underlying the Mini-MAC items: Helpless/Hopeless, Anxious Preoccupation, Fighting Spirit, Cognitive Avoidance, and Fatalism. Absolute, incremental, and parsinmonious fit indices showed a high significant level of acceptance confirming a good performance of the measurement model. The instrument showed sufficient reliability and convergent validity demonstrated by acceptable values of composite reliability (CR =0.93–0.97), and average variance extracted (AVE= 0.66 - 0.93), respectively. The square roots of AVE were higher than factor-factor pairs correlations, and the Heterotrait-Monotrait ratio of correlations values were lesser than 0.85, indicating an acceptable discriminant validity. Conclusions: reliability; and both convergent and discriminant validity tests indicated that The Arabic version of the Mini-MAC had a good performance and may serve as a valid tool measuring psychological responses to cancer diagnosis and treatment.