Background: Older patients suffering from a combination of psychiatric disorders and physical illnesses and/or dementia are called Double Care Demanding patients (DCDs). Special wards for DCDs within Dutch nursing homes (NHs) and mental health care institutions (MHCIs) offer a unique opportunity to obtain insight into the characteristics and needs of this challenging population.Methods: This observational cross-sectional study collected data from 163 DCDs admitted to either a NH or a MHCI providing specialized care for DCDs. Similarities and differences between both DCD groups are described. Results: Neuropsychiatric symptoms were highly prevalent in all DCDs but significantly more in MHCI-DCDs. Cognitive disorders were far more present in NH-DCDs, while MHCI-DCDs often suffered from multiple psychiatric disorders. The severity of comorbidities and care dependency were equally high among all DCDs. NH-DCDs expressed more satisfaction in overall quality of life.Conclusions: The institutionalized elderly DCD population is very heterogeneous. Specific care arrangements are necessary because the severity of a patient's physical illness and the level of functional impairment seem to be equally important as the patient's behavioural, psychiatric and social problems. Further research should assess the adequacy of the setting assignment and the professional skills needed to provide adequate care for elderly DCDs.