Mycotic pseudoaneurysm of the aorta is a rare disease in childhood. We report on two cases which were diagnosed in an unselected general pediatric population within an 8-month period. The first case was a 16-month-old toddler with a normal cardiac history who presented with purulent pericarditis due to group A streptococcus and subsequent pseudoaneurysm formation of the ascending aorta while convalescing from varicella infection. The second case was a 14-year-old girl with a previously undiagnosed coarctation of the aorta who developed a Staphylococcus aureus aortitis in the dilated poststenotic segment with pseudoaneurysm formation and infiltration into the adjacent lung tissue. In both cases parenteral antibiotic therapy was administered over 10 and 4 days, respectively, followed by emergency surgery consisting of aneurysmectomy, coarctectomy (case 2), and in situ homograft implantation. Recovery was uneventful. In both cases early institution of a femorofemoral cardiopulmonary bypass prevented a fatal outcome despite intraoperative rupture of the pseudoaneurysm.