Contrast enhanced cross sectional echocardiography is a new method for the real-time evaluation of regional myocardial perfusion. Two patients with a history of anteroseptal myocardial infarction and echocardiographically detected septal dyskinesia were examined by this new method. The first patient had two severe stenoses of the left anterior descending coronary artery and normal echocontrast opacification of the interventricular septum caused by collaterals from the right coronary artery. The second patient had good patency of left anterior descending coronary artery and no septal opacification. Thus contrast enhanced cross sectional echocardiography can be used to assess the importance of collateral blood flow in the myocardium.