Reliable treatment burden measures are needed given the aging population and the associated increase in multimorbidity and polypharmacy. Treatment burden is defined as the effort to care for one’s health and the resulting impact on one’s daily life. This study aimed to translate the Multimorbidity Treatment Burden Questionnaire (MTBQ) for French-Canadians and assess its reliability and validity. The MTBQ was translated and tested with cognitive debriefing interviews, and the French version (MTBQ-F) was then administered 2 times among 105 participants. Reliability and validity were examined using the intra-class correlation coefficient (ICC), Cronbach’s alpha, and Spearman’s correlations. The median global MTBQ-F scores were 32.69 (interquartile range [IQR]: 21.15-48.08) and 30.77 (IQR: 21.15-46.15) for the first and second administrations, respectively. Test-retest (ICC: 0.73; 95% CI: 0.63-0.81) and internal consistency reliability (Cronbach’s alpha: 0.80) were good. There was a moderate positive correlation between the MTBQ-F score and the number of self-reported conditions (rho: 0.28). This valid instrument could identify patients experiencing a high treatment burden and assess the impact of interventions among them.