There is intense scientific interest in the possibility that the acute administration of a fibrinolytic agent might be of benefit to patients with acute myocardial infarction. This hypothesis, which will soon be tested in a major trial by the National Heart, Lung, and Blood Institute, has emerged from a confluence of advances in three areas: increased knowledge about the role of thrombosis in myocardial infarction, the development of fibrinolytic agents and the recognition that ischemic myocardial tissue might be salvaged from necrosis by timely reperfusion. Examination of the manner in which these areas of knowledge developed and interacted not only illuminates our path to this specific therapeutic possibility, but also demonstrates the indirect and stuttering manner in which important new ideas often evolve.