In this study we have examined the epidermal growth factor receptor gene (EGFR) region for the amplification of novel expressed sequences in 28 glioblastoma tumors and two cell lines with EGFR gene amplification. Southern analysis with expressed sequence tag (EST) probes revealed instances of amplification for 11 of 13 loci investigated. Northern blot analysis with the same probes indicated that three ESTs identified transcripts that are over-expressed in cell lines having corresponding sequence amplification. The determination of increased dosage and transcript levels for multiple expressed sequences raises the possibility that there are genes in addition to EGFR whose elevated expression contribute to the biologic behavior of tumors with amplification of this region.