Small RNA (sRNA) molecules have gained much interest lately, as recent genome-wide studies have shown that they are widespread in a variety of organisms. The relatively small family of 10 known sRNA-encoding genes in Escherichia coli has been significantly expanded during the past two years with the discovery of 45 novel genes. Most of these genes are still uncharacterized and their cellular roles are unknown. In this survey we examined the sequence and genomic features of the 55 currently known sRNA-encoding genes in E.coli, attempting to identify their common characteristics. Such characterization is important for both expanding our understanding of this unique gene family and for improving the methods to predict and identify sRNA-encoding genes based on genomic information.