Mycotic aneurysms (MA) are an uncommon complication of infectious endocarditis. Septic emboli are thought to be the precipitating event in their development, but the evidence for this is sparse. We present three cases in which septic embolic occlusion preceded MA development at the occlusion site, suggesting that documented angiographic emboli in patients with infectious endocarditis and bacteremia constitute a risk factor for MA formation. Two adult patients with a history of intravenous drug use and one child with congenital heart disease are described. They were all diagnosed with infectious endocarditis and developed neurological symptoms during their hospital course. Initial catheter-based cerebral angiograms demonstrated vascular occlusions, which were followed by the development of MA at the same sites within 1 month. Septic emboli, documented on cerebral angiogram, in patients with infectious endocarditis may precede the appearance of MA. Patients with angiographic occlusions in the setting of endocarditis warrant close follow-up.