The KEGG databases are a key resource for the Japanese GenomeNet service, providing comprehensive information on genes, genomes, and biological pathways. The KEGG databases include the PATHWAY, GENES, and LIGAND databases, along with EXPRESSION, BRITE, and SSDB. The PATHWAY database contains information on molecular interaction networks, while the GENES database provides gene and protein information from genome sequencing projects. The LIGAND database includes data on chemical compounds and reactions relevant to cellular processes. The EXPRESSION database stores microarray gene expression profiles and yeast two-hybrid system data, while the BRITE database contains binary relations for gene and protein interactions. The SSDB database is a new resource for exploring all protein-coding genes in complete genomes and identifying functional links and ortholog groups. KEGG data are represented as graphs, enabling the detection of graph features related to biological functions. The KEGG databases are updated daily and freely available. The GENES database contains gene entries from various organisms, and gene annotations are performed using ortholog identifiers. The SSDB database is used to identify functional links and ortholog groups, and it is integrated with other databases for gene annotation. The PATHWAY database contains pathway diagrams and ortholog group tables, and it is used to understand higher-order functional meanings of genes and genomes. The KEGG databases are accessed through various methods, including text searches, pathway information examination, and genome map browsing. Other databases in GenomeNet include DBGET/LinkDB, which is a retrieval system for all GenomeNet databases, and computational tools for sequence similarity searches and motif searches. All KEGG data are freely available via anonymous FTP. The work was supported by grants from various Japanese organizations.The KEGG databases are a key resource for the Japanese GenomeNet service, providing comprehensive information on genes, genomes, and biological pathways. The KEGG databases include the PATHWAY, GENES, and LIGAND databases, along with EXPRESSION, BRITE, and SSDB. The PATHWAY database contains information on molecular interaction networks, while the GENES database provides gene and protein information from genome sequencing projects. The LIGAND database includes data on chemical compounds and reactions relevant to cellular processes. The EXPRESSION database stores microarray gene expression profiles and yeast two-hybrid system data, while the BRITE database contains binary relations for gene and protein interactions. The SSDB database is a new resource for exploring all protein-coding genes in complete genomes and identifying functional links and ortholog groups. KEGG data are represented as graphs, enabling the detection of graph features related to biological functions. The KEGG databases are updated daily and freely available. The GENES database contains gene entries from various organisms, and gene annotations are performed using ortholog identifiers. The SSDB database is used to identify functional links and ortholog groups, and it is integrated with other databases for gene annotation. The PATHWAY database contains pathway diagrams and ortholog group tables, and it is used to understand higher-order functional meanings of genes and genomes. The KEGG databases are accessed through various methods, including text searches, pathway information examination, and genome map browsing. Other databases in GenomeNet include DBGET/LinkDB, which is a retrieval system for all GenomeNet databases, and computational tools for sequence similarity searches and motif searches. All KEGG data are freely available via anonymous FTP. The work was supported by grants from various Japanese organizations.