Loss of heterozygosity at specific chromosomal locations has been taken as evidence of a tumor suppressor gene located in that area. We performed a genomic allelotyping study on 46 childhood brain tumors of different histopathological types in order to identify and confirm common areas of deletion in different tumor types. Two hundred microsatellite DNA probes equally distributed over the 22 autosomes were applied, covering the genome in steps of approximately 25 cM. Our results confirm frequent loss of heterozygosity of chromosome arms 9q, 10q, 11p, 11q, 16q, and 22q in high-grade gliomas, medulloblastomas, and ependymomas. In addition, we found a new region of loss on chromosome segment 2p21-23 affected predominantly in high-grade gliomas and medulloblastomas.