We studied the clinical and angiographic outcomes in 8 patients with acute left main coronary artery obstruction. Intracoronary thrombolysis with 1.2 x 10(5) units of urokinase was performed in 3 patients during preparation for percutaneous transluminal coronary angioplasty (PTCA), and failed in all 3 cases. In 2 patients, the left main coronary artery was recanalized by intracoronary thrombolysis with 3.6 and 4.8 x 10(5) units of urokinase, respectively. PTCA was attempted either before or after intracoronary thrombolysis in 5 patients and achieved reperfusion in all 5 cases. However, 2 of the 8 patients had persistent high-grade residual stenosis 69% and 89% luminal reduction, respectively. Emergency coronary artery bypass grafting was successfully performed in these 2 patients, and both are currently alive. Although intraaortic balloon counterpulsation was performed in all 8 patients, 2 died acutely from pump failure in the catheterization laboratory. One patient died later due to congestive heart failure. The factors favoring survival were right coronary artery dominance and a well-developed collateral circulation. Our findings suggest that PTCA is a useful strategy for reperfusion following acute left main coronary artery occlusion. When PTCA cannot achieve sufficient revascularization, emergency coronary artery bypass grafting should be performed. To control pump failure, intraaortic balloon counterpulsation is insufficient in some cases and more aggressive measures may be required.