Coronary thrombolysis can be achieved with several lytic agents administered via the intravenous or intracoronary routes. Streptokinase, when administered intravenously, produces coronary thrombolysis in from 34 to 75 per cent of patients. Intravenous administration has the advantage of rapid administration without the risks or delays inherent in the performance of cardiac catheterization, although lysis rates are lower than those achieved with intracoronary administration. Administration early after infarction (in the first 4 hours) is associated with improved ventricular function and reduced mortality.