Coronary angiography followed by percutaneous transluminal coronary angioplasty and/or intracoronary streptokinase infusion was performed in 50 patients 288 ± 162 min after the onset of symptoms of acute myocardial infarction. Subocclusion of the infarct-related vessel was found in 5 patients, all of whom had angioplasty of the residual stenosis. Recanalization was achieved in 37 patients (success rate 82%). There was no procedure-related death. One patient died 4 days after the intervention. Control coronary angiography 5 ± 2 months after the procedure in 35 of 42 patients with recanalization documented recurrence of stenosis or reocclusion in 8 (23%). Comparison of preintervention and control angiograms in 33 patients showed an increase in left ventricular ejection fraction from 55 ± 8 to 61 ± 13%, p < 0.001, in patients with collaterals to the infarct-related vessel and/or recanalization within 180 min after the onset of pain, and from 55 ± 9 to 59 ± 8%, nonsignificant, in patients with recanalization later than 180 min and without collaterals. At follow-up 7 ± 4 months after the procedure, 1 patient had died and 36 (86%) were asymptomatic. Good long-term results can be achieved at a reasonable risk by coronary angioplasty with or without thrombolysis in evolving myocardial infarction. Left ventricular function is better preserved in patients with collaterals and/or early recanalization.