Abstract: Aim of the study: Assessing the cross-cultural psychometric properties of the Dutch-MQoL for breast cancer patients. Methods: 26 patients were recruited at the Antwerp University Hospital. Eligible patients filled in the MQoL on different moments in time in order to evaluate clinimetric properties. To determine the validity; MQoL was correlated to the EORTC QLQ-C30. Internal consistency was analysed using Cronbach's and test-retest reliability was determined by ICC. For statistical responsiveness, S.E.M and MDC were calculated. Results: A strong correlation was found between the 'QoL score' of the MQoL and the domain 'existential wellbeing' of the EORTC QLQ-C30 (r = 0.72). An excellent test-retest reliability (ICC (1,1)) was demonstrated with intraclass coefficients ranging from 0.82 to 0.92. A MDC in total score of only 1.22 (12%) was seen, needed to detect a factual change within a patients' QoL. Psychometric properties of the Dutch MQoL were found comparable to the properties of the original questionnaire. Conclusion: The Dutch version of the MQoL is a valid and reliable questionnaire for breast cancer patients and shows statistical responsiveness. Due to the strong to excellent reliability, this version of the MQoL is useful in clinical as well as scientific setting.