Background: People with an intellectual disability have a higher risk of developing mental disorders compared to the general population. Available evidence suggests those with an intellectual disability receiving inpatient treatment in general psychiatric wards may have certain unique characteristics. Method: Data gathered from a retrospective review of records of adults with intellectual disability admitted to general psychiatry wards in a tertiary psychiatric hospital in Singapore were analysed. Results: Of 290 adults with intellectual disability, 62.8% were males. The median age was 38 years. The median length of stay was 12 days and over 80% had at least one previous admission. Nearly 80% had a mild intellectual disability and 64.5% had at least one psychiatric comorbidity, the majority having schizophrenia or psychotic disorder. Physical aggression was the most common primary reason for admission. Conclusions: The specific profile of patients identified in the study would be helpful in determining priority areas for the development of specialist psychiatric services for people with intellectual disability.