OBJECTIVES: To examine the relationship between symptoms of depression and mortality in older people. DESIGN: Prospective longitudinal study. SETTING: Fifty-three general practices in the United Kingdom. PARTICIPANTS: Thirteen thousand ninety-seven people aged 75 and older participating in the Medical Research Council Trial of the Assessment and Management of Older People in the Community. MEASUREMENTS: Depression was measured using the 15-item Geriatric Depression Scale (GDS-15); the main outcome was all-cause mortality. RESULTS: Morbidity, disability, and lifestyle factors can explain most of the observed relationship between symptoms of depression and mortality (hazard ratio=1.75, 95% confidence interval (CI)=1.53-1.99), but after mutual adjustment for these factors, subjects who reported six or more symptoms of depression on the GDS-15 were still 27% more likely to have died by the end of the follow-up period than those below the threshold for depression (95% CI=1.11-1.45). CONCLUSION: The findings from this study suggest that depression confers a small risk for mortality in older people, not explained solely by poor health. The results support the encouragement of effective diagnosis, treatment, and support for individuals with depression as highlighted by the World Health Organization and the UK National Service Framework for older people.