Background: Integrative and conjugative elements (ICEs) are bacterial self-transmissible elements that encode a full complement of machinery for conjugation as well as excision from the chromosome and onward conjugative transfer.They can promote their own mobilization and potentially that of other hitch-hiking mobile genetic elements, and thus contribute to horizontal transfer of virulence determinants, antibiotic-resistance genes and other bacterial traits.As sequenced genome databases expand exponentially, ICEs have been identified in increasing numbers.Recently we have developed a web-based tool ICEr for rapid identification of ICEs in bacterial genomes, supported by the back-end database ICEberg.Methods: The web-based database ICEberg currently contained details of 428 ICEs found in representatives of 124 bacterial species, and a collection of over four hundred directly related references [Bi, et al., Nucleic Acids Research, 2012].Although ICEs vary in sequence and genetic organization, sequence comparison and phylogenetic analysis showed showed that many share related integrase, maintenance and/or transfer genes.ICEberg thus classified 344 ICE entries as 28 specific families firstly based on integrase similarity and secondarily core structure synteny.Recently an online tool ICEr have been delevoped for identification of ICEs in bacterial genome sequences.ICEr integrated the Vmatch program to detect the ICE-flanking direct repeats and HMMER3 for the homology searches of the specific ICE repertoire, including integrase, relaxase and/or type IV secretion system, which had been archived within ICEberg.Users can upload their bacterial nucleotide sequence with or without annotation.With parallel computing cluster architecture, typically ICEr idenify the putive ICEs on the fly in a matter of 1~5 minutes.For example, it takes ca.1 minute for the annotated 5.3 Mb Klebsiella pneumoniae clinical isolate HS11286.Two novel ICEs were found within the HS11286 chromosome, an 62-kb element encoding virulence determinants was inserted into an asn tRNA gene site while another with the size of 56 kb into a phe tRNA gene site [Liu, et al., Journal of Bacteriology, 2012].Results: We propose that the unique web-based resource to provide comprehensive information about ICEs found in bacteria, such as ICEr, will facilitate efficient, multidisciplinary and innovative exploration of bacterial ICEs and be of particular interest to researchers in the broad fields of prokaryotic evolution, pathogenesis, biotechnology and metabolism .