To assess the benefit of immediate surgical reperfusion over conventional medical treatment during the first acute evolving transmural myocardial infarction, 68 patients presenting within 4 hours of onset of chest pain were randomized into a medical group and a surgical group. Both groups were comparable for age, sex, coronary risk factors, location of infarct, and coronary anatomy. Radionuclide global ejection fraction at 48 hours after admission was 45 +/- 15% for the medical group versus 50 +/- 15% for the surgical group; at 3 months, ejection fraction values were 51 +/- 13% and 51 +/- 13%, respectively (p = NS). The average radionuclide wall-motion scores (normal, 3) at 3 months were 2 +/- 0.6 for the medical group and 2 +/- 0.7 for the surgical group. There were three (8.8%) early and four (11.7%) late deaths in the medical group and only one (2.9%) early death in the surgical group. Urgent surgical reperfusion in acute evolving myocardial infarction is a safe and effective procedure that appears to reduce early and late mortality but does not appear to improve left ventricular function.