In a controlled randomized study of 328 consecutive patients admitted within 24 hours after the onset of acute myocardial infarction, 163 patients received a sodium nitroprusside infusion during 24 hours, followed by six times a day 5 mg isosorbide dinitrate for seven days and 165 patients received a glucose 5% infusion. Excluded from the study were patients with either pulmonary edema and/or cardiogenic shock, two or more previous myocardial infarctions or a systolic blood pressure of less than 95 mmHg just before entering the study. Sodium nitroprusside was titrated in such a way that systolic blood pressure was kept between 95 and 105 mmHg. Standard medical treatment for both groups was the same. CK-MB was sampled every four hours until peak value was reached. Endpoint of the study was a significant reduction in mortality within a week after starting treatment.