Nowadays, one of the important directions of ensuring the national security of Ukraine is the fight against organized crime, which, taking into account the complicated socio-political situation, economic instability and development of the criminal situation, appears to be escalating and spreading dramatically. That is of concern due to the possibility of using individual criminal organizations and organized groups by foreign secret services in order to carry out reconnaissance, subversion, terrorist and other illegal activities, provoke destabilization of public life and intimidation of citizens, cause damage to the state security of Ukraine.That is why the article is devoted to a research of сarrying out special assignment to expose criminal activities of the organized group or criminal organization that is one of the most effective measures of pretrial investigation of the suppressed activities of organized crime. Despite the fact, that with the adoption of Criminal Procedure Code of Ukraine, investigative actions are being studied quite actively, mentioned above type of covert investigative (detective) actions is studied in sections of the general issues, and the works that would have considered the сarrying out special assignment, or its problematic issues as a sub- ject of self-study are practically absent. This is especially true when we talk about the сarrying out special assignment by the Security Service of Ukraine.So author draws attention to current issues of understanding the essence and content of сarrying out special assignment to expose criminal activities of the organized group or criminal organization comparing it with the corresponding operational-investigative action. It is said that the current status of the legal regulation of сarrying out special assignment, although it seems sufficiently complete, but at a thorough examination it appears to be in need of improvement. Furthermore, inter-branch relationships, correlation of concepts and definitions, the organization and tactics especially of law enforcement activities require deep consideration. Therefore it is offered to expand researches of the theory and practice issues of the mentioned above type of covert investigative (detective) action particularly conducted by the Security Service of Ukraine.