Previous studies have suggested that a substantial proportion of the patients with intellectual disabilities (ID) in the high security psychiatric hospitals (HSPHs) should be transferred to more appropriate services to cater for their specific needs in the longer term. The individual and placement needs of high secure psychiatric patients detained under the legal category of mental impairment or severe mental impairment were assessed in a cross-sectional survey. Patients had a large number of needs (on average 10.8), about a third of which were rated as unmet and therefore represented significant continuing problems. Approximately one-third of the sample could be moved out of HSPHs if appropriate alternatives were available. Factors associated with the continued need for high security included higher treatment and security needs, younger age, recent violent conduct and their index offence profile. High security services are still required for a number of patients with ID. New and existing services need to be configured to meet specific profiles of need and provide long-term rehabilitation and specialist care. This was part of a larger project funded by grants from the High Security Psychiatric Services Commissioning Board and Department of Health.