Nine consecutive patients with penetrating missile wounds of the heart were evaluated by M-mode and two-dimensional echocardiography for localization of retained missile fragments noted to be moving in synchrony with the heart by fluoroscopy. Echocardiography precisely located all 12 moving fragments: 2 in the pericardium, 5 in the anterior right ventricular wall, 3 in the free left ventricular wall, 1 in the interventricular septum and 1 in the right posterior atrioventricular groove. Five patients had echocardiographic evidence of pericardial effusion and only one manifested a wall motion abnormality, indicating that direct myocardial perforation does not always result in detectable intrapericardial bleeding or asynergy. Localization of the missile fragments to be in danger of endocardial perforation, in danger of eroding the right coronary artery and creating a clinically unsuspected membranous ventricular septal defect led directly to surgical intervention in three different patients. In all three, intraoperative echocardiography quickly localized the missile fragments and significantly reduced patient cardiopulmonary bypass time. In the remaining six patients, localization of missile fragments well within the myocardium with no danger of erosion led to decisions against surgical removal.