The Skeletal Gene Database (SGD) is an integrated resource that provides comprehensive information about bone-related genes, mRNA, and proteins expressed in human and mouse, with rich links to numerous other electronic tools. SGD contains expressed sequence tag (EST) data from all the skeletal-related cDNA libraries that are available to the public. It supplies the query/data access analytic tools for users to search and compare each gene expressed in skeletal tissue(s). The results derived from EST tissue expression profiling will allow users to get the data on the mRNA copy numbers of each gene expressed in each tissue and its normalized value. From the SGD, researchers can obtain information regarding the name, symbol, size, exon/intron number, chromosomal location, LocusLink, and related disease (if any is known) of each gene. This electronic compendium also furnishes information on the protein of the corresponding gene including the protein size (amino acid number and molecular weight). It provides swift and ready access to other useful databases including OMIM, UniGene and PUBMED. The data will be updated regularly in step with current and future research, thereby providing what we hope will serve as a highly useful source of information and a powerful analytic tool to the scientific community. Published 2002 Wiley-Liss, Inc.