BioGRID is a comprehensive and freely accessible database that houses physical and genetic interaction datasets from various species, including *Saccharomyces cerevisiae*, *Caenorhabditis elegans*, *Drosophila melanogaster*, and *Homo sapiens*. The database, available at http://www.thebiogrid.org, includes over 116,000 interactions and has recently added more than 30,000 interactions from 5778 sources through extensive curation of the primary literature for *S. cerevisiae*. BioGRID offers an internally hyper-linked web interface for rapid search and retrieval of interaction data, with full or user-defined datasets available for download in tab-delimited text and PSI-MI XML formats. Pre-computed graphical layouts of interactions are also provided in various file formats. The database supports the creation of user-customized graphs with embedded protein, gene, and interaction attributes using the Osprey visualization system. BioGRID has been queried over 38 million times since its inception and continues to expand its coverage and functionality, including the addition of quantitative genetic interactions and curated post-translational modifications. The database is supported by a robust web interface and a MySQL 4.1 database management system, and it is regularly updated to ensure accuracy and reliability.BioGRID is a comprehensive and freely accessible database that houses physical and genetic interaction datasets from various species, including *Saccharomyces cerevisiae*, *Caenorhabditis elegans*, *Drosophila melanogaster*, and *Homo sapiens*. The database, available at http://www.thebiogrid.org, includes over 116,000 interactions and has recently added more than 30,000 interactions from 5778 sources through extensive curation of the primary literature for *S. cerevisiae*. BioGRID offers an internally hyper-linked web interface for rapid search and retrieval of interaction data, with full or user-defined datasets available for download in tab-delimited text and PSI-MI XML formats. Pre-computed graphical layouts of interactions are also provided in various file formats. The database supports the creation of user-customized graphs with embedded protein, gene, and interaction attributes using the Osprey visualization system. BioGRID has been queried over 38 million times since its inception and continues to expand its coverage and functionality, including the addition of quantitative genetic interactions and curated post-translational modifications. The database is supported by a robust web interface and a MySQL 4.1 database management system, and it is regularly updated to ensure accuracy and reliability.