The effects of residual stenosis after intracoronary thrombolysis (ICT) on the hospital course and on left ventricular function were investigated in 94 patients with acute myocardial infarction. The in-patient hospital events including death, post-infarction angina, and re-infarction occurred in 6 of 24 (25%) patients with 100-99% residual stenosis (Group I), 18 of 55 (32.7%) patients with 95-90% stenosis (Group II) and one of 15 (7%) patients with 75% or less stenosis (Group III), suggesting that the presence of severe residual stenosis could be associated with the occurrence of in-patient hospital events. However, re-infarction occurred in only 3.6% of Group II patients. In an analysis of left ventricular function, global and regional wall motion was significantly improved in this group of patients, compared with patients who had no reperfusion (Group I). What is more, the degree of the improvement in wall motion in Group II, despite the severe stenosis, was the same as that in Group III with 75% or less stenosis. It was concluded that further intervention following thrombolysis may not be necessarily required for patients who underwent reperfusion without filling delay, even if the residual stenosis is greater than 90%.