In comparison to cancer in adults, virtually all cancers of childhood and adolescence are rare. Nevertheless, there is a rather ill-defined group of tumors that are not only exceptionally rare but also do not fall into the major clinical categories of childhood cancers. Thus, a substantial proportion of these exceptionally rare tumors are not registered within clinical registries or prospective therapy optimization studies. Only recently, major attention has been drawn to the diagnostic assessment and treatment of children and adolescents with such orphan diseases. In 2006, the RARE TUMOR GROUP has been established within the German Society of Pediatric Oncology and Hematology (GPOH). This working group includes experts from Pediatric Oncology, Pediatric Surgery, Pediatric Pathology, Medical, Dermatologic and Radiation Oncology as well as Pediatric Epidemiology. The major aim of the rare tumor group is to integrate these patients into the diagnostic and therapeutic network successfully established in the pediatric oncologic society. Thus, the group aims at fostering the exchange of experience in the treatment of rare tumors between medical centers and to include patients in the diagnostic and therapeutic reference network. In addition, an information platform shall be established that will be accessible to treating physicians, patients and their parents. More information and better registration shall be established by active data accrual on a regular basis and by the implementation of a data base including diagnostic and therapeutic data of patients with rare tumors. These efforts as presented in this article as well as an intensified international collaboration will allow us to provide children and adolescents with rare tumors the best possible care.