['While the death rate from acute coronary syndromes (ACS) has been in decline for more than 50 years, out-of-hospital mortality remains high despite improvements in care.', 'To evaluate the importance of out-of-hospital mortality and identify the main predictors of in-hospital and 1-year mortality in France.', 'Analyses were based on data from the French MONICA population-based registry, which included all cases of ACS occurring in people aged 35-74 years during 2006 in three geographic areas in France. We first evaluated out-of-hospital mortality; then, using data from patients with incident ACS who reached hospital alive, Cox models were performed to determine the main predictors of 1-year mortality. The number of attributable deaths was assessed for variables of interest.', 'After 1-year follow-up, case-fatality was 29.3% for incident events (n=2547); the proportion of out-of-hospital deaths was 70.3%, and 91.5% of deaths occurred in the 28 days following the ACS. On multivariable analysis, the number of attributable deaths associated with three scenarios (out-of-hospital life-and-death emergency, hospitalization before ACS occurrence, and lack of coronary angiography) was 130 (accounting for 59% of deaths occurring after reaching the hospital) during 1-year follow-up. These scenarios corresponded to patients with an initial severe clinical presentation in whom rates of use of specific treatments and invasive procedures were very low.'] Is the major element of 1-year prognosis in acute coronary syndromes severity of initial clinical presentation : Results from the French MONICA registries?