Background: Case fatality after myocardial infarction (MI) among patients admitted to the hospital may differ between men and women and blacks and whites. Furthermore, a different pattern of sex and race differences in case fatality may occur when coronary deaths outside the hospital are included in the analysis. The ARIC study provides community-based data to examine 28-day case fatality rates after coronary heart disease (CHD) events. Method and Results: Surveillance of out-of-hospital CHD deaths and hospitalized MI was conducted in 4 U.S. communities from 1987 to 1993. Hospital discharges and death certificates were sampled, medical records abstracted, and interviews conducted with witnesses of out-of-hospital deaths. MI and out-of-hospital death classifications followed a standard algorithm. Linkage of hospitalized MIs to fatality within 28 days ensured complete ascertainment of case fatality rate. Comorbidities and complications during hospital stay were compared to assess possible explanatory factors for differences in case fatality. Overall, age-adjusted 28-day case fatality (MI plus CHD) was higher in black men compared with white men (odds ratio 1.78, 95% confidence interval 1.4-2.2) and in black women compared with white women (odds ratio 1.5, 95% confidence interval 1.2-2.0). Although men had higher overall case fatality rates than did women, this difference was not statistically significant. After a hospitalized MI, 28-day case fatality rate was not statistically significantly different between men compared with women or blacks compared with whites. Conclusion: Race and sex differences in case fatality after hospitalized MI were not evident in these data, although when out-of-hospital deaths were included, men and blacks were more likely than women and whites to die within 28 days of an acute cardiac event. A majority of deaths occurred before hospital admission, and additional study of possible reasons for these differences should be a priority.