With the help of operative-investigative infiltration, law enforcement bodies and special services have the opportunity to accumulate necessary information about the members of criminal groups, relationships in the criminal environment (including with criminals operating on the territory of other states), the time and methods of committing illegal acts, the goals pursued, etc. In order to obtain information during contacts with representatives of the criminal environment in such a way that they are not aware that special investigative measures are being carried out regarding them, veiled penetration is applied in this field. Prerequisites for the application of such a way of gathering information are provided by the special investigation legislation of several states. At the same time, it contains contradictory positions regarding the possibility of infiltrated persons to commit, even formally, illegal acts, determined by their being in the sphere of a criminal environment. In order not to admit violations of legal norms and avoid theoretical discrepancies, it is necessary to explain the meaning of the notion of "operative-investigative infiltration" and to scientifically justify the importance of this special investigative measure. All these aspects identify the pursued goal and materialize the topicality of the subject to scientific research.