In this article, we describe the use of the BioMart data management system to provide integrated access to International Knockout Mouse Consortium (IKMC) data and other related mouse resources. The IKMC is currently mutating all mouse protein-coding genes in embryonic stem (ES) cells using gene targeting and gene trapping approaches. The BioMart portal allows researchers to identify and obtain IKMC knockout vectors, ES cells and mice for genes of interest. Gene annotation, expression, phenotype and disease data is also integrated from external BioMarts, allowing selection of IKMC products by a wide variety of criteria. These products are invaluable for researchers involved in the elucidation of gene function and the role of individual genes in human disease. Here, we describe these datasets in more detail and illustrate the functionality of the portal using several examples.