Hypertension (HT) and diabetes mellitus (DM) lead to structural and functional cardiac impairment and worsen the prognosis after myocardial infarction (MI). However, the prognosis of male or female patients with the coexistence of HT and DM after MI has not been clearly demonstrated. The study sample comprised 4317 consecutive patients with an acute MI from a prospective nationwide survey conducted in 1992, 1994 and 1996 in all 25 coronary care units operating in Israel. The in-hospital, 30-day and 1-year outcome of diabetic hypertensive patients (n=546) was compared with that of diabetic normotensive patients (n=547) and with that of nondiabetic hypertensive patients (n=1192) and nondiabetic normotensive subjects (n=2032). The crude in-hospital, 30-day and 1-year mortality rates of diabetic hypertensive patients (11.7, 16.5 and 27.6%, respectively) were significantly higher than those of the diabetic normotensive patients (9.5, 15.4 and 22.9%, respectively) and nondiabetic hypertensive patients (7.1, 11.6 and 17.6%, respectively). Kaplan-Meier survival curves showed increased mortality rates during the 1-year follow-up in diabetic hypertensive patients. Adjusted risk for 1-year mortality was increased in diabetic patients. However, the risk was similar in diabetic hypertensive and normotensive patients (hazard ratio (HR) 1.55, 95% confidence interval (CI) 1.25-1.93, and 1.62, 95% CI 1.29-2.04, respectively). Adjusted Kaplan-Meier survival curves of diabetic hypertensive patients converged with those of the diabetic normotensives. The existence of DM increases the 1-year mortality after MI by about 60%. However, controlled hypertension did not worsen the outcome of diabetic male or female patients after MI.