A molecular understanding of porcine reproduction is of biological interest and economic importance. Our Midwest Consortium has produced cDNA libraries containing the majority of genes expressed in major female reproductive tissues, and we have deposited into public databases 21,499 expressed sequence tag (EST) gene sequences from the 3' end of clones from these libraries. These sequences represent 10,574 different genes, based on sequence comparison among these data, and comparison to existing porcine genes indicate as many as 4,652 are novel. Computer analysis identified sequences that are expressed in specific pig tissues or organs, and confirmed the broad expression in pig for many genes ubiquitously expressed in human tissues. Furthermore, we have developed computer software to identify sequence similarity of these pig genes with their human counterparts, and to extract the mapping information of these human homologues from genome databases. We used this software to localize 61 genes on the porcine physical map of chromosomes 5, 10, and 14. Thus our sequence data is useful in accelerating mapping studies and will be useful in understanding pig reproductive biology.