Infective endocarditis is rare in children. Its incidence is higher among patients with congenital heart diseases. Neurological symptoms caused by emboli can be the first manifestation of the disease and can lead to diagnosis.

We present an infant after cardiosurgery for coarctation of the aorta, in whom unusual formation of mycotic aneurysm at the operated place occurred. The patient was admitted to the emergency department with feeding difficulties. Physical examination revealed left hemiparesis and a new heart murmur on the apex. Laboratory and imaging tests confirmed the diagnosis of infective endocarditis with a 6-mm vegetation on the mitral valve complicated with ischaemic stroke. A chest X-ray performed in the sixth week of treatment revealed an oval-shaped shadow in the area of the descending aorta. Computed tomography angiography confirmed a mycotic aneurysm formation in that location. The patient was operated on with good outcome.