Introduction: Restricted and repetitive behaviours (RRB) are actions or interests demonstrated in the form of repet- itive motor movement that interferes with one’s daily performance. Repetitive Behavior Scale-Revised (RBS-R) is a self-report questionnaire designed to assess the variety and severity of RRB in people with Autism Spectrum Disorder (ASD) comprehensively. The purpose of the current study was to investigate the validity and reliability of the Ma- lay version of RBS-R questionnaire. Methods: The cross-cultural adaptation of the RBS-R was performed following established guidelines. The questionnaire was assessed its content and face validity before it was administered to 34 parents or caregivers of children with ASD to determine the internal consistency reliability. Content validity in- dex, face validity index and Cronbach’s alpha were calculated. Results: The Malay version of RBS-R showed the scale-level content validity with an average index (S-CVI/Ave) of 0.97 and a universal agreement index (S-CVI/UA) of 0.84. Meanwhile, scale-level face validity with an average index (S-FVI/Ave) of 0.97 and a universal agreement index (S-FVI/UA) of 0.90 were derived, indicating that the Malay version of RBS-R questionnaire was relevant, clear and comprehensible. All subdomains showed the Cronbach’s alpha coefficient of over 0.7, ranging from 0.758 to 0.914 indicating it was a reliable tool. Conclusion: This study showed good level of content validity index, face validity index and internal consistency reliability of the questionnaire. These study findings indicated the practicality of the Malay version of RBS-R to assess RRB in children with ASD. Further research on construct validity is recommended.