The objective of this report was to examine the effects of sex and diabetic status on in-hospital mortality and 12 year survival following hospital discharge among 4109 patients hospitalized between 1974 and 1986 with acute myocardial infarction. Sixteen general hospitals in the Worcester, MA, standard metropolitan statistical area were included. The age-adjusted in-hospital case-fatality rate was significantly higher in diabetic women (23.3%) than in non-diabetic women (18.9%) (p < 0.05) while no significant difference was noted among men. Over a 12 year follow-up period, the relative risk of dying among diabetic men was 1.56 times that for non-diabetic men (95% CI, 1.43, 1.68). Diabetic women were 1.57 times as likely to die as non-diabetic women (95% CI, 1.45, 1.73). Among non-diabetic subjects, men had a 17% excess risk of death compared to women (95% CI, 1.09, 1.25). No significant difference in long-term mortality was noted among diabetic persons. Thus, the "female advantage" observed in the non-diabetic population was eliminated among the diabetic patients. Randomized clinical trials are needed in the diabetic population to identify specific therapies to reduce their increased risk of death.