Fibrinolytic therapy is effective in reducing the extent of myocardial infarction by lysing intracoronary clots. An overview of twelve trials of prolonged intravenous infusion of SK showed a highly significant reduction in short term mortality. Intra coronary SK infusion achieved reperfusion of the coronary artery in 60 to 90 p. 100 of patients and improvement of left ventricular function was reported. Mortality was also significantly reduced at 6 months. The frequency of bleeding was relatively low and ventricular arrhythmias were not a serious problem. High dose brief duration intravenous SK therapy achieved reperfusion of the occluded coronary artery in 44 to 60 p. 100 of patients. Left ventricular function was also improved. An Italian multicentre trial has shown a significant decrease in the overall hospital mortality of a randomized population. There is no evidence that UK was more effective than SK. New fibrinolytic agents (T-PA, acylated SK-plasminogen activator), with more fibrin specific activity, were successful in inducing coronary thrombolysis in patients with acute myocardial infarction. The rate of reocclusion was about 20 p. 100 and additional stabilising procedure (percutaneous transluminal coronary angioplasty) was necessary in many patients.