Aim. The study was aimed to examine the appropriateness of using the Mini Nutritional Assessment to screen for risk of under- and over-nutrition in adults with intellectual disabilities. Background. Persons with intellectual disabilities are at increased risk of malnutrition, but routine monitoring of their nutritional conditions are not widely done. Design. The study purposively recruited 104 institutionalised adults (≥19 years old) with intellectual disabilities to serve as participants. Methods. Participants were interviewed with a structured questionnaire to elicit personal data, health-related information and answers to items in the Activities of Daily Living and the Mini Nutritional Assessment scales and measured for anthropometrics. Biochemical data were taken from their routine medical measurements. Each subject was graded with the Mini Nutritional Assessment that adopted Taiwanese-specific anthropometric cut-off points (T1) and an alternative version that omitted the body mass index item (T2). Results. Both Mini Nutritional Assessment versions were able indentifying individuals at risk of malnutrition among adults with intellectual disabilities and rated comparable proportions of patients malnourished (6·7 and 5·8% for Mini Nutritional Assessment-T1 and Mini Nutritional Assessment-T2, respectively) or at risk of malnutrition (14·4 and 17·3%, respectively). Persons with cerebral palsy were at greater risk of malnourishment than persons with other disabilities. Conclusion. The Mini Nutritional Assessment is appropriate for screening for under- and over-nutrition in adults with intellectual disabilities. The Mini Nutritional Assessment (especially the version without body mass index) can make routine monitoring of nutritional status of these patients an easier task. However, further studies are needed to develop subtype-specific versions (tools) as various subtypes of intellectual disability are associated with different nutritional problems. Relevance to clinical practice. The Mini Nutritional Assessment can serve as a tool for routine screening for under- and over-nutrition in persons with intellectual disabilities.