On the basis of structural similarity between the m-and rRNA binding sites which under* lies the molecular mechanism of the autogenous control of expression of the rplJL genes, mediated in prokaryotic organisms by ribosomal protein LIO, we attempted to find the potential mRNA target sites in S. griseus and S. coelicolor. The potential targets found in both species of Streptomyces are of highly conserved structure and contain elements similar with the LIO binding domain of the 23S RNA. Compared to the LIO, mRNA targets of Enterobacteria, Thermotoga maritima and Synechocystis, the target sites of Streptomyces contain a larger number of conserved and specific stru ctural elements, similar in both analyzed species. Comparison of the structural organi zation of the «Streptomyces» and «Enterobacterial» types of the LIO mRNA targets with the structure of the LIO binding domain in the 23S RNA reveals that the elements, conserved in all the mentioned targets, are located in the ssA and dsA regions. The structure of the potential LIO mRNA target sites, which mimic the rRNA target of the regulatory ribosomal protein LIO, gives evidence for the autogenous LlO-mediated control of expression of the rplJL genes in Streptomyces.