Regulatory small RNAs (sRNAs), also known as non-coding RNA, are not translated into proteins and widespread in prokaryotes and eukaryotes. sRNAs involve in multiple fundamental cellular events. They are emerging regulatory elements that are gaining momentum. Knowledge of sRNA largely originates from eukaryotes. Prokaryotic sRNAs, particularly those of pathogen are only recently explored. The main types, function, and methodology to predict pathogen sRNAs are summarized in this review. Special focus is sRNAs regulating pathogen gene expression, particularly that of Mycobacterium tuberculosis, which is hitherto the most successful pathogen afflicting mankind. J. Cell. Physiol. 226: 968–973, 2011. © 2010 Wiley-Liss, Inc.