We established the Pig Genome Database (PiGenome) for pig genome research. The PiGenome integrates and analyzes all publicly available genome-wide data on pigs, including UniGenes, sequence tagged sites (STS) markers, quantitative trait loci (QTLs) data, and bacterial artificial chromosome (BAC) contigs. In addition, we produced 69,545 expressed sequence tags (ESTs) from the full-length enriched cDNA libraries of six tissues and 182 BAC contig sequences, which are also included in the database. QTLs, genetic markers, and BAC end-sequencing information were collected from public databases. The full-length enriched EST data were clustered and assembled into unique sequences, contigs, and singletons. The PiGenome provides functional annotation, identification of transcripts, mapping of coding sequences, and SNP information. It also provides an advanced search interface, a disease browser, alternative-splicing events, and a comparative gene map of the pig. A graphical map view and genome browser can map ESTs, contigs, BAC contigs (from the National Institute of Animal Science), Sino-Danish Pig Genome Project transcripts, and UniGene onto pig genome sequences which include our 182 BAC contigs and publically available BAC sequences of the Wellcome Trust Sanger Institute. The PiGenome is accessible at http://pigenome.nabc.go.kr/ .