It is difficult to define what is considered a “rare” tumor in children. The rarity can be relative, i.e., common in adults but the occurrence in children is rare (such as breast cancer or colorectal carcinoma). Rarity can also be an absolute term, defined by the number of cases per 100,000 or per million. Other opinions suggested that tumors are considered rare when there is no unified protocol of management. The European Cooperative Study Group for Pediatric Rare Tumors (EXPeRT) defined a rare childhood cancer as one that has an incidence rate less than 2 per million per year, is not considered in clinical trials, or both. This chapter discusses some of the rare tumors in children. This includes lung tumors such as inflammatory myofibroblastic pseudotumor, pulmonary hamartoma, pulmonary carcinoid tumor, and pulmonary metastatic tumors. It also includes cardiac tumors, Thymic neoplasms, and peripheral nerve sheath tumors.