To achieve optimal myocardial revascularization and prevent rethrombosis of the infarct-related coronary artery, percutaneous transluminal coronary angioplasty (PTCA) was attempted in 18 patients with evolving acute myocardial infarction (9 anterior and 9 inferior) after administration of intracoronary streptokinase. PTCA was attempted 338 ± 151 minutes after the onset of symptoms. After thrombolytic therapy, 11 patients had a severe residual stenosis and 7 a persistent total occlusion of the infarct-related coronary artery. PTCA was successful in 13 of 18 patients: in 9 of 11 with coronary stenoses and in 4 of 7 with total coronary occlusions. PTCA reduced the severity of the coronary lesion from 91 ± 2% to 27 ± 7% (p < 0.001), and the transstenotic pressure gradient from 38 ± 5 to 6 ± 2 mm Hg (p < 0.01). One patient in cardiogenic shock died during urgent coronary surgery after unsuccessful PTCA. After PTCA, all patients received heparin and antiplatelet agents. One patient had reinfarction with reocclusion of the infarct-related artery 5 days after PTCA. The other 12 patients had an uneventful hospital course, and cardiac catheterization before hospital discharge (8 to 17 days) revealed reocclusion of the infarct-related coronary artery in 3 and persistent patency in 9. Persistent patency of the infarct-related artery was associated with preservation of left ventricular end-diastolic volume (initial 86 ± 6 ml/m2, follow-up 91 ± 6 ml/m2), and improvement in left ventricular ejection fraction in some patients. © 1985.