While coronary arteries of anomalous origin are uncommon, some forms seem to be predisposed to atherosclerosis. Very few cases of percutaneous transluminal coronary angioplasty (PTCA) in anomalous arteries have been reported. We report a case of successful PTCA of the left anterior descending artery through an anomalous left main coronary artery originating from the right aortic sinus in a 65-year-old man with unstable angina. PTCA was performed using an 8 F 3.5 cm right Judkins guiding catheter to dilate a discrete 90% stenosis of the left anterior descending artery. After PTCA, the patient became symptom free. Using the proper guiding catheter, PTCA can be performed in coronary arteries of anomalous origin with excellent results.