Myocardial bridge is a cluster of myocardial fibers crossing over the epicardial coronary arteries at a distance. It is most frequently seen on the left anterior descending artery. Involvement of the left circumflex coronary artery is very rare. A 63-year-old man presented with chest pain radiating to the left shoulder. Physical examination was normal. The electrocardiogram showed slight lateral ST-segment changes. Treadmill electrocardiography revealed significant lateral ST and T wave changes. Coronary angiography showed normal coronary arteries except for significant systolic narrowing of the mid-circumflex artery after the first obtuse marginal branch. The patient was discharged with beta-blocker therapy. He had no recurrent chest pain during eight months of follow-up.