The transcription of small stable nontranslated RNA genes (class III genes), directed by RNA polymerase III, is strictly regulated in accordance with the physiological state of the cell (growth rate, cell cycle stage, apoptosis, etc.) Posttranslational modifications of RNA polymerase may play an important role in class III gene transcription regulation. Using computational programs that search for potential posttranslational modification sites in proteins (MotifScan, NetPhos 2.0, and Yin-Yang 1.2), possible sites of phosphorylation were identified in all 17 subunits of human RNA polymerase III, and possible sites of reciprocal phosphorylation and glycosylation (the "yin-yang" sites) were identified in 13 subunits. Among them, 17 phosphorylation sites in seven subunits proved to be conserved in H. sapiens, Saccharomyces cerevisiae, and Schzosaccharomyces pombe, including two yin-yang sites in two subunits. The data obtained can be used for experimental identification of RNA polymerase III modification sites in vivo in cells that are in different physiological states.