In large necropsy studies dissecting intramyocardial hematoma (DIH) with serpiginous tracts across the myocardial fibers has been reported in both the septum and the left ventricle free wall. We studied 15 patients admitted to the hospital with acute myocardial infarction (AMI) in which DIH was demonstrated by either transthoracic and/or transesophageal and confirmed intraoperatively or by necropsy. In nine patients the hemorrhagic dissection was predominantly in the septum and in the remaining it was in the free wall of the left ventricle (LV). Myocardial infarction involved the left ventricular inferior wall in two, and the anterior wall in 13 patients. The overall mortality was 47%, and in the group with septal hematoma it reached to 78%. Echocardiography disclosed the various acoustic densities of the evolving intramyocardial hematoma, its extension through the hemorrhagic dissection, its spontaneous reabsorption, as well as its communication with the ventricular cavities. Echocardiography is the method of choice for the noninvasive diagnosis of patients with suspected myocardial rupture and intramyocardial dissection postmyocardial infarction.