An open-access, web-available portal that integrates available data of bat genomes and genes. BGD hosts data from six bat species, including two megabats and four microbats. Users can query the gene annotations using efficient searching engine, and it offers browsable tracks of bat genomes. BGD is the first repository centralizing the genomes and genes of bat species. The database not only provides a large resource for the bat researches, but also supplies a platform for comparative genomic analysis.