New molecular techniques such as cDNA, protein or antibody arrays allow for high-throughput identification of thousands of potentially disease-related markers on the genome, transcriptome and proteome level. Major disadvantages of such studies are the enormous costs and the need for unfixed tissues, disallowing comprehensive large-scale studies. Consequently, validation studies including large sets of clinically well-defined tissue samples are now necessary to identify those genes or proteins with true impact on the course of disease which will eventually lead to therapeutic applications. Tissue microarray technology overcomes the bottleneck of traditional tissue analysis and allows it to catch up with the rapid advances in lead discovery. Current applications and the future potential of tissue microarray technology in cancer research and diagnosis are discussed.