Ascertaining when and where genes are expressed is of crucial importance in order to understand the physiological role of a given gene/protein and the interactions between them. In addition, the normal expression patterns can then be compared to those observed in a variety of pathological conditions to identify pathological hallmarks of gene expression. The EURExpress, an integrated project funded by the EU under the VI Framework proposes a transcriptome-wide acquisition of expression patterns chiefly by means of in situ hybridization (ISH) with non-radioactive probes and will use this data to establish a web-linked, interactive digital transcriptome atlas of embryonic mouse.