The authors report the case of a 7 year-old boy, in whom a mycotic aneurysm of the lobar inferior left pulmonary artery had been found in the course of a staphylococcal endocarditis of the tricuspid valve. Surgical removal of the aneurysm was followed by a thrombosis of this artery. This is a rare complication after infective endocarditis. Analysis of literature data shows that the rupture of these aneurysms frequently occurs; therefore, systematic surgical treatment is recommended whenever the anatomic conditions make it possible.