Two-dimensional echocardiography (2-D echo) was performed for six postoperative patients who had acute myocardial infarction (AMI)-like electrocardiographic (ECG) changes. All but one, who had coronary T waves, demonstrated abnormal Q waves in V1-V4, decreased amplitude of R waves, and low voltage in limb leads. ST elevation was also observed. Abnormal Q waves in V1-V4 began to resolve in a few days and the QRS complex reverted to normal within one month; however, coronary T waves were observed for at least three months. In the remainder one, persistent Q waves were present from the onset. 2-D echo, performed simultaneously with ECG, showed akinesis or dyskinesis accompanied by ventricular dilatation, not only at the anterior septum, anterior wall and around the apex, but in more extensive areas in four of five cases with abnormal Q waves in V1-V4. In two other cases, which showed abnormal Q or coronary T waves alone, akinesis was limited to the anterior septum and to the septal site and anterior wall of the apex. All abnormal findings on 2-D echo completely resolved within one month, as the ECG findings returned to normal. Compared with typical AMI showing abnormal Q waves in V1-V4, asynergy was recognized in more extensive areas and abnormal wall motion indices significantly improved in the postoperative cases. In the postoperative cases with AMI-like ECG, the CPK-MB fraction increased; however, the peak level of CPK was lower than that in typical AMI. On the basis of these results, transient AMI-like ECG findings in postoperative cases are due to extensive myocardial damage, which is probably derived from focal myocytolysis.