Previous research has established a relation between depression at the time of cardiac hospitalization and patient mortality. The objective of this study was to examine the role of depressive history and symptomatology during hospitalization on 5-year all-cause mortality after admission for an acute coronary syndrome. We recruited 750 patients who had unstable angina pectoris and myocardial infarction from 12 coronary care units between 1997 and 1999. Measurements included sociodemographic and clinic data and the Beck Depression Inventory (BDI). Data were linked to an administrative database to determine 5-year all-cause mortality. Survival data were adjusted using a Cox's proportional hazards model. One hundred seventy-four participants (23.2%) self-reported a history of depressed mood for >2 weeks, 235 (31.3%) had elevated BDI scores at index hospitalization, with 105 (14.0%) reporting persistent depressive symptomatology. One hundred fifteen participants (15.3%) died by 5 years after hospitalization. After adjusting for prognostic indicators, such as cardiac disease severity, medical history, and smoking, depressive symptomatology during hospitalization was significantly predictive of mortality, but depressive history was not. Hazard ratios associated with BDI scores <10 versus those > or =10 at hospitalization ranged from 1.90 (95% confidence interval 1.12 to 3.24) at 2 years to 1.53 (95% confidence interval 1.04 to 2.24) at 5 years. In conclusion, the significance of depressive symptomatology at the time of, but not before, hospitalization underlines the need for early identification of increased distress and renews calls to identify treatments that not only improve quality of life but also decrease the risk of mortality.