We determined in-hospital and 1-year prognoses after acute myocardial infarction (MI) in 5,839 consecutive patients derived from 14 of 21 coronary care units in Israel during 1981-1983. Age-adjusted in-hospital mortality was 23.1% in 1,524 women and 15.7% in 4,315 men (p less than 0.0005). One-year age-adjusted mortality rates in patients surviving hospitalization were 11.8% in women and 9.3% in men (p = 0.03). Cumulative age-adjusted 1-year mortality rates were 31.8% in women and 23.1% in men (p less than 0.0005). Relative odds of mortality, covariate-adjusted for major prognostic factors that included age, prior MI, congestive heart failure, and infarct location by electrocardiogram, indicated that female gender was independently and significantly associated with increased mortality both during hospitalization (relative odds, 1.72; 95% confidence interval, 1.45-2.04) and at 1 year after discharge (relative odds, 1.32; 95% confidence interval, 1.05-1.66). In separate multivariate analyses for each gender, a major factor that emerged as a predictor of outcome in women, but not in men, was a reported history of diabetes mellitus, both for in-hospital mortality and for 1-year mortality. However, even in the nondiabetics in this population, female gender was a significant, independent predictor of in-hospital mortality. The findings of the present study substantiate that women fare worse than men after suffering an acute MI, that increased age does not fully account for the increased mortality in women, and that diabetic women are at particularly high risk once MI has occurred.