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Among a variety of regulatory signals functioning in the chromosomal DNA promoters are the mostly studied and, probably, the least understood. Canonical sequences revealed by statistic analysis are the main promoter-specific determinants, which are common for all promoters recognized by vegetation form of RNA polymerase. These elements are composed of 12 base pairs (bp), however only 7 or 8 of them are usually found in the promoter DNA and approximately 10 % of promoters have less than 7 canonical bp. That means that very low level of correspondence to the canonical elements may be sufficient for transcription initiation. However any combination of 4-8 canonical bp could be found in the genomic DNA of E.coli many times providing a possibility for faulty transcription initiation. Nonetheless exhausting production of false mRNA is not observed in the bacterial cell. That means that transcription machinery employs additional promoter-specific signals to distinguish promoter DNA from another sequences. Identification of additional promoter-specific elements as well as their detailed characterization is a long term objective of this study. Results: Non-canonical elements were recently revealed in the sequence of bacterial promoters. The significance in their presence was evaluated using non-promoter DNA fragments as well as sequence data of the E.coli genome. Elements were identified with statistical significance comparable to or even higher than for canonical hexamers. These elements are suggested as additional signals for promoter-search algorithms. Availability: The list of biochemically characterized promoter sequences with indicated non-canonical elements is availabl