The diagnosis and treatment of individuals with problems involving both psychiatry and neurology have become more sophisticated in recent years, but these advances may be difficult to implement in the modern health care environment. For 16 years, an inpatient Geriatric Treatment Center within a state mental hospital has been used to diagnose and treat older persons with complex neuropsychiatric disorders. Eight illustrative cases are presented of patients with major behavioral dysfunction that could not be managed effectively in other health care facilities. After neuropsychiatric evaluation and behavioral neurology consultation, all had neurologic diagnoses established as the cause of their presentation. Seven improved with appropriate treatment, of whom one could return to independent living, and the eighth died and had an autopsy diagnosis of his disease at a nearby academic medical center. This series highlights the value of collaboration between psychiatry and neurology for evaluation and treatment of older patients with neuropsychiatric problems not easily accommodated by many existing health care settings.