The RNA editing is one of the post-transcriptional modifications which prepare RNA for fulfilling its function. It is well known that editing is a common process for most of eukaryotic organisms (from protozoan to human) and for some groups of viruses, however its mechanism is specific for species, genera and kingdoms. Up to now RNA editing is well characterized for few species only. It is suggested that substitutional RNA editing is conducted by deaminase so as it does not lead to the sugar-phosphate backbone brakeage.