Abstract. The application of security measures is not only an effective means of ensuring that evidence is used in criminal proceedings, but also a guarantee of the protection of the rights and legitimate interests of citizens who are involved in criminal proceedings, state activities to combat crime. The Code of Criminal Procedure of the Russian Federation provides for a system of security measures, including the preservation of authentic data in secret, the assignment of a pseudonym and the obtaining of a sample signature from a protected person. This measure may be applied at the very outset of the proceedings, at stage of the institution of criminal proceedings. In practice, however, there are problems with the application of security measures in verifying the basis for the institution of criminal proceedings. Purpose: to analyze the problems of development of modern criminal procedure legislation in the field of ensuring the safety of participants in criminal proceedings at the stage of the institution of criminal proceedings. Methods: the author applies empirical methods of comparison, description, interpretation; theoretical methods of formal and dialectical logic. Specific scientific methods are used: legal-dogmatic and the method of interpreting legal norms. Results: the study reveals the features of the use of such a security measure as the assignment of a pseudonym and seisure of authentic data from the verification of the crime report during the institution of criminal proceedings. The author’s version of Part 9 of Art. 166 of the Code of Criminal Procedure of the Russian Federation is proposed with a view to making it more effective in investigative practice.