A fusiform aneurysm of the left main coronary artery without associated obstructive disease was detected in a 77-year-old patient with severe unstable angina treated with systemic thrombolysis. The authors emphasize the following features: (1) unusual location of the aneurysm, (2) absence of concomitant obstruction in this age group, and (3) clinical efficacy of thrombolysis and subsequent long-term oral anticoagulation.