Cyanobacteria and the cyanophage that infect these bacteria are abundant throughout fresh water and marine ecosystems. Unfortunately, the knowledge of genomic interaction between these cyanophages and their hosts are limited due to the lack of integration of the cyanogroup information. To remedy this deficiency, a Cyanogroup Genomics Knowledge Base (CGKB) for cyanophages and cyanobacteria has been initiated: http://www.cvanogroup.com/. This knowledge base includes: (1) the literature database of freshwater and marine cyanogroups; (2) the genomic database of these cyanogroups including NCBI GenBank data and sequence data from both our laboratory and that of other researchers; (3) data analysis - DNA, protein sequences and phylogenetic analysis; (4) relevant links for the cyanogroups. Regular updates of the local database will be performed to maintain the high accuracy of the analysis and BLAST searches. CGKB also provides sequence and phylogenetic analysis tools for users to search and query any related information stored in the database.