BackgroundStudies internationally have found that a high treatment burden is associated with several long-term conditions and poor quality of life. ObjectivesTo translate, culturally adapt, and provide evidence of reliability, validity, and factor structure of the Multimorbidity Treatment Burden Questionnaire for use among Arabic-speaking adults with multimorbidity. MethodsStandard guidelines for the cross-cultural adaptation of self-report measures were followed. The original 10-item MTBQ was translated into Arabic by professional translators using forward-backward translation. An expert group, including the creator of the MTBQ, participated in the cultural adaptation and content validity, followed by cognitive interviewing and pilot testing. The questionnaire was then tested on 177 Arabic-speaking patients with multimorbidity recruited from community pharmacies in the United Arab Emirates. The distribution of responses, dimensionality, internal consistency reliability, and construct validity were examined. ResultsThe content validity of the MTBQ-A was good (Content Validity Index = 0.94), and cognitive interviews found that the items were well understood. The scale showed positive skewness and high floor effects. Factor analysis supported a two-dimensional structure (factor loadings >0.4): factor one was named “Self-management and social support,” and factor two was named “Burden of visiting health care services and health care professionals”. The questionnaire had good internal consistency (α = 0.83). As predicted, a higher MTBQ score in both factors was associated with poor health-related quality of life in all dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression (p values < 0.05); and negatively correlated with self-efficacy in taking medication (p < 0.01) and in learning about medication (p < 0.01). ConclusionsThe Arabic MTBQ is a valid and reliable measure of treatment burden with good construct validity and internal consistency. This easy-to-understand questionnaire can be used to assess the perceived treatment burden among Arabic-speaking patients with multimorbidity.