The authors report a case of traumatic left ventricular aneurysm, presenting with recurrent cerebral embolism, 36 years after a thoraco-brachial bullet wound. The 58 year old man had no symptoms of angina or particular cardiovascular risk factors. The ECG showed changes of chronic anterior wall infarction, observed 10 years previously on a routine preoperative recording. There was a calcified circular para-apical shadow on chest X-Ray. The antero-apical region showed hypofixation on myocardial scintigraphy, and hypokinesia on isotopic angiography. The coronary arteries were normal. Indium III platelet marking revealed a focus of hyperfixation within the left ventricle. At surgery, a true calcific para-apical left ventricular aneurysm was discovered, containing a fresh thrombus. This lesion was resected. Peroperative Indium III platelet test confirmed that the thrombus was the site of high uptake. The surgical result was good at 6 months follow-up. This case illustrates: the value of the Indium test which would appear to be a very specific and sensitive method of detecting intraventricular thrombi. This test, which appreciates the thrombotic activity of intracardiac masses is a useful complement to other non-invasive methods such as 2D echocardiography; the special characteristics of post-trauma left ventricular aneurysms which are rare, often diagnosed late, at the time of complications such as systemic embolism, commonly pose medico-legal problems, and for which surgical treatment seems to be indicated in symptomatic patients.