BACKGROUND A development of a needs-led mental health classification system based on the Health of the National Outcome Scales (HoNOS) has previously been developed. AIMS To extend the needs-based mental health (MH) clusters to accommodate the additional needs of people accessing UK intellectual disabilities health services. METHOD Hierarchical cluster analysis was performed on assessment data from 18 National Health Service (NHS) provider organisations. The statistical results were clinically shaped through multi-disciplinary workshops. The resulting clusters were combined with six independently rated measures for a second data collection exercise. Based on these data, refinements were made before performing internal and external validity checks. RESULTS Eight additional clusters for people with health needs associated with their intellectual disabilities were produced. Three described primarily physical health (PH) needs, four described needs arising from behaviours which challenged (with/without autism) whilst one described people with generally low needs. Together, these covered 83.4% of cases with only a 10% overlap. The clusters were replicable and had clinical utility and validity. CONCLUSIONS It was possible to extend the needs-led mental health classification system to capture the additional needs of people accessing UK intellectual disability services.