Genes up-regulated in tumor cells provide attractive anticancer therapeutic targets. Although the general underlying mechanism for the increased expression in tumors is unknown, tumor-specific up-regulation of some genes can be attributed to aberrant DNA amplification, a phenomenon common to many tumors. Using a computational method, we constructed a general transcriptome map with the human genomic sequences and expressed sequence tags in the public database. The transcriptome map revealed nonrandom chromosomal regions (termed region of increased tumor expression) where clusters of genes exhibited increased expression in the 10 tumor tissue types tested. These genomic regions often correspond to experimentally verified tumor amplicons. Our large-scale transcriptome analysis led to identification of many additional chromosomal regions with increased tumor expression, regions that represent potential tumor amplicons.