The risk factors for mistreatment of older people include age, race, low income, functional or cognitive impairment, a history of violence, and recent stressful events. There is little information in the literature concerning the clinical profile of mistreated older people. To describe the characteristics of abused or neglected patients and to compare the prevalence of depression and dementia in neglected patients with that of patients referred for other reasons. A case control study. Baylor College of Medicine Geriatrics Clinic at the Harris County Hospital District (Houston, Texas). Forty-seven older persons referred for neglect and 97 referred for other reasons. Comprehensive geriatric assessment. Standard geriatric assessment tools. There was a statistically significant higher prevalence of depression (62% vs 12%) and dementia (51% vs 30%) in victims of self-neglect compared to patients referred for other reasons. This is the first primary data study that highlights a high prevalence of depression as well as dementia in mistreated older people. Geriatric clinicians should rule out elder neglect or abuse in their depressed or demented patients.