Invasive pulmonary Aspergillus, although rare in the general population, represents an important cause of morbidity and mortality among immunosuppressed patients. However, mediastinal invasion by Aspergillus is very uncommon, with few cases documented in the literature. Among 13 immunosuppressed pediatric patients recently diagnosed with invasive pulmonary aspergillosis, 3 have had posterior mediastinal invasion with severe complications. Rupture of a mycotic aortic aneurysm occurred in 2 patients, one of whom was operated on successfully. The infection involved the spinal cord with severe neurologic sequelae in 2 patients. We report our experience to make our colleagues aware of this problematic disease, which may be more prevalent in the current population of highly immunosuppressed pediatric patients.