Myocardial bridge is often considered to be a simple anatomical variation often observed during coronary angiography. The responsibility of this condition for myocardial ischaemia is however uncommon and the physiopathological mechanisms are not well understood. The authors report 6 cases of myocardial bridge associated with myocardial infarction of unstable angina. The main features of this condition are discussed with respect to a review of the literature. Patients are usually young and male; the left anterior descending artery is the most commonly affected vessel: factors triggering ischaemia are discussed: coronary spasm, tachycardia and thrombosis at the site of the myocardial bridge. The diagnosis can only be made by coronary angiography showing reduction of the systolic diameter of the artery which may be accentuated by certain pharmacological tests such as injection of glyceryl trinitrate as used in the series.