The authors tested the relationship between clinically diagnosed delirium during hospitalization and increased mortality after accounting for pre-hospital measures of global cognition, physical functioning, and medical comorbidity. Patients (N=102), 53 of which were hospitalized during the course of a year, received the Mini-Mental State Exam, Physical Self-Maintenance Scale, Cumulative Illness Rating Scale, and 15-item Geriatric Depression Scale. Mortality rates were determined at discharge and after 3 years. Patients who developed delirium did not differ on pre-hospitalization levels of depression, global cognitive performance, physical functioning, or medical comorbidity. Three-year mortality in the hospitalized subjects was 75% for delirium patients vs. 51% for control patients (risk ratio=2.24). Delirium occurring during hospitalization places elderly subjects at long-term risk of mortality. This effect is not accounted for by earlier measures of cognitive, functional, or health status.