A 71-year-old man presented with fever and positive blood cultures for methicillin-sensitive Staphylococcus aureus 4 days after an uncomplicated intra-luminal abdominal aortic aneurysm repair. Investigations looking for a source of sepsis including computerized tomography scans, transoesophageal echocardiography, a bone scan and repeated chest X-rays, did not reveal an infective focus. Gallium 6 7 scintigraphy, however, showed a focus of tracer uptake in the region of the aorto-cardiac junction consistent with the presence of an abscess. Coronary angiography later opacified an aneurysmal cavity arising from the right sinus of Valsalva which was confirmed to be a mycotic aneurysm on thoracotomy. This is a rare case of early detection of a cardiac mycotic aneurysm by Gallium 6 7 scintigraphy.