BACKGROUND: Dispositional optimism, defined in terms of life engagement and generalized positive outcome expectancies for one's future, may be related to lower cardiovascular mortality. We aimed to determine whether dispositional optimism is a stable trait over time and whether it is independently related to lower cardiovascular mortality in elderly men. METHODS: In a cohort study with a follow-up of 15 years, we included 545 (61.4%) of 887 men, aged 64 to 84 years, who were free of preexisting cardiovascular disease and cancer and who had complete data on cardiovascular risk factors and sociodemographic characteristics. Dispositional optimism was assessed using a 4-item questionnaire in 1985, 1990, 1995, and 2000. In Cox proportional hazards models, the first 2 years of observation were excluded. RESULTS: Optimism scores significantly decreased over 15 years, but showed temporal stability (reliability coefficients, 0.72 over 5 years and 0.78 over 15 years; P < .001). Optimists in 1985 had a hazard ratio for cardiovascular mortality of 0.45 (top tertile vs lowest tertile; 95% confidence interval, 0.29-0.68), adjusted for classic cardiovascular risk factors. The risk of cardiovascular death was inversely associated with increased tertiles of dispositional optimism (P < .001 for trend). Similar results were obtained using 1990 data after additional adjustment for depression (assessed by the Zung Self-rating Depression Scale). CONCLUSION: Dispositional optimism is a relatively stable trait over 15 years and shows a graded and inverse association with the risk of cardiovascular death.