An algorithm for recognition of prokaryotic ribosomal binding sites is suggested. The parameter library contains weight matrices for mapping of gene starts in various bacterial genomes. Comparison of the ribosome binding starts in different taxonomic groups demonstrates that the signals in Gram-positive bacteria are stronger than in Gram-negative bacteria, and in particular, Enterobacteria. The recognition matrices are available by e-mail misha@imb.imb.ac.ru.