Gene amplification has been associated both with tumor stage and progression in human gliomas. Several distinct amplified loci have been identified by comparative genomic hybridization and Southern blot analysis. It has been increasingly recognized that amplified domains comprise multiple genes. Here, we demonstrate amplification of up to 12 different genes from an amplified domain at 12q13-15 that has been found in approximately 15% of astrocytomas and glioblastomas. The amplified genes were GLI, WNT1, MDM2, SAS, CDK4 OS-4, GAS16, GAS27, GAS41, GAS56, GAS 64 and GAS89. In one glioblastoma all 12 amplified genes were also found to be expressed. These results strongly warrant the search for as yet unidentified genes in regions previously reported to be amplified.