INTRODUCTION: The aim of this study was to assess the reliability and validity of a modified Malaysian version of the Medication Adherence Reasons Scale (MAR-Scale). METHODS: In this cross-sectional study, the 15-item MAR-Scale was administered to 665 patients with hypertension who attended one of the four government primary healthcare clinics in the Hulu Langat and Klang districts of Selangor, Malaysia, between early December 2012 and end-March 2013. The construct validity was examined in two phases. Phase I consisted of translation of the MAR-Scale from English to Malay, a content validity check by an expert panel, a face validity check via a small preliminary test among patients with hypertension, and exploratory factor analysis (EFA). Phase II involved internal consistency reliability calculations and confirmatory factor analysis (CFA). RESULTS: EFA verified five existing factors that were previously identified (i.e. issues with medication management, multiple medications, belief in medication, medication availability, and the patient's forgetfulness and convenience), while CFA extracted four factors (medication availability issues were not extracted). The final modified MAR-Scale model, which had 11 items and a four-factor structure, provided good evidence of convergent and discriminant validities. Cronbach's alpha coefficient was > 0.7, indicating good internal consistency of the items in the construct. The results suggest that the modified MAR-Scale has good internal consistencies and construct validity. CONCLUSION: The validated modified MAR-Scale (Malaysian version) was found to be suitable for use among patients with hypertension receiving treatment in primary healthcare settings. However, the comprehensive measurement of other factors that can also lead to non-adherence requires further exploration.