Literature of the past ten years is reviewed to examine psychosocial, psychiatric, organic, and general medical causes of psychotic symptoms in persons over age 65. Being bedfast with poor caretaker relationships and being socially isolated are risk factors for psychosis among elderly persons. A thorough history is essential to differential diagnosis. Psychiatric causes to be ruled out include schizophrenia; depression, including mania; dementia and delirium; paranoid state; and late-life delusional disorder. Perhaps the most common etiology is cognitive impairment, generally attributable to Alzheimer's disease or multi-infarct dementia. Organic or toxic etiologies need to be ruled out, especially in persons with visual hallucinations. Drug toxicity, a structural brain lesion, or a subtle seizure disorder should be considered. If symptoms are not alleviated when psychosocial triggers or underlying toxic, organic, or medical causes are addressed, patients may respond to supportive therapy and low doses of high-potency neuroleptics. The clinician should keep in mind that older adults are highly sensitive to the side effects of these agents.