Availability of statistically sufficient numbers of tumor samples and other biomaterials in high quality together with corresponding clinical data is crucial for biomedical research. Tumor repositories from individual scientists are mostly not sufficient to satisfy these criteria, especially since pediatric tumors are rare. In 2000 three centralized tumor repositories (neuroblastoma in Cologne, nephroblastoma in Würzburg, hepatoblastoma, brain tumors in Bonn) have been established by the "German Competence Net Pediatric Oncology und Hematology". The aim was to collect biomaterial including tumor samples, normal tissue, and blood in high quality for research and diagnostic purposes at a central institution. Informed consent of the parents or patients is a prerequisite for scientific use of the samples and is requested by the therapy trial. The samples are collected according to accepted standards and shipped in the specially designed Tumorbox. The tumor repository organizes the distribution of the samples to the cooperating diagnostic laboratories. The number of collected tumor samples has increased over the years. In 2000, samples from 200 patients were collected while the patient number increased to 321 in 2005. Over the years the tumor repositories collected more than 7,150 samples (fresh frozen tumor, fresh frozen normal tissue, and blood). Through links with clinical trial databases the samples can be connected with clinical data. 12 of 14 applications for tumor material to be used in specific scientific projects have been approved by an independent supervisory board. The establishment of central tumor repositories represents a major step for biomedical research activities and quality control in pediatric oncology.