Posttranscriptional regulation of gene expression mediated by small RNAs plays an important role in the virulence of pathogenic microorganisms. We have detected the expression of the following Mycobacte rium avium genes situated in intergenic loci and coding for small RNAs: MAV-0380-0381 (4.5S RNA), MAV-1034-1035 (trans-encoded small RNA), MAV-1415-1416 (antisense or trans-encoded small RNA), and MAV-1531-1532 (processed 5'-UTR of the 16S rRNA gene). The above-named small RNAs are the first members of the small noncoding RNA class detected in M. avium. © D.V. Ignatov, L.G. Mefodieva, K.B. Majorov, T.A. Skvortsov, T.L. Azhikina, 2012.