Alterations in the genome that lead to changes in DNA sequence copy number are a characteristic of Glioblastomas (GBs). Microarray-based comparative genomic hybridization (array-CGH) is a high-throughput technology that allows the hybridization of genomic DNA onto conventional cDNA microarrays, normally used in expression profiling, to analyze genomic copy number imbalances. In this way, thousands of genes can be reviewed in a high resolution analysis to define amplicons and to identify? candidate genes showing recurrent genomic copy number changes in GB tumors.