The National Cancer Institute's Cancer Genome Anatomy Project (CGAP) is developing publicly accessible information, technology, and material resources that provide a platform for the interface of cancer research and genomics. CGAP's efforts have focused toward (1) building and annotating catalogues of genes expressed during cancer development, (2) identifying polymorphisms in those genes, and (3) developing resources for the molecular characterization of cancer-related chromosomal aberrations. To date, CGAP has produced more than 1,000,000 expressed sequence tags, approximately 3,300,000 serial analysis of gene expression tags, and identified more than 10,000 human gene-based single-nucleotide polymorphisms. To enhance access to these datasets by the research community, a new Cancer Genome Project web site (http://cgap.nci.nih.gov/) is being introduced. The web site includes genomic data for humans and mice, including transcript sequence, gene expression patterns, single-nucleotide polymorphisms, clone resources, and cytogenetic information. Descriptions of the methods and reagents used in deriving the CGAP datasets are also provided. An extensive suite of informatics tools facilitates queries and analysis of the CGAP data by the community. One of the newest features of the CGAP web site is an electronic version of the Mitelman Database of Chromosome Aberrations in Cancer.