To evaluate the benefits of intravenous streptokinase (SQIV) in acute myocardial infarction (AMI), we joined a group of ten Mexican university hospitals, that were coordinated by the National Institute of Cardiology of Mexico. We included patients less than 70 years of age admitted to the hospital with less than 6 hours from the onset of chest pain during their first myocardial infarction. All patients had ST segment elevation of 1.5 mm or more, and none had contraindication for SQIV. They received 1.5 millions of SQIV in one hour. Reperfusion criteria included absence of pain, ST segment reduction and a rapid rise and fall of enzyme levels. Angiographic criterion for reperfusion was the permeability of the affected coronary vessel. Of 66 patients studied, 57 (86%) had clinical reperfusion; of the 24 available angiographic studies, 92% demonstrated reperfusion. Eight (12%) of the patients had minor complications and 7 (10%) had serious complications. There were 0 deaths. We concluded that SQIV is a useful therapeutic procedure, easy to perform in general hospitals.