The reform of control and supervisory activities of business entities, which has been going on for several years, is aimed at increasing the level of security and eliminating excessive administrative burden. At the same time, one of the fundamental principles formulated in modern management science states that prevention is more important than enforcement. In such circumstances, it is crucial to achieve the goals of the ongoing reform of control and supervision activities, such as the reorientation of control (supervisory) bodies from the detection and suppression of offenses to their prevention. The implementation of this direction is conducted through the introduction in various areas of a set of measures aimed at preventing violations of mandatory requirements. The purpose of the study is to systematize the forms and methods used by antimonopoly units to prevent violations. The methods include formal-legal, formal-logical, interpretation of law, as well as general scientific methods. According to the results of the study, the author concludes that the implementation of various forms and methods of state control directly aimed at preventing violations of mandatory requirements, such as preventive measures, administrative prevention measures, and preliminary control, plays an increasingly important role in the activities of antimonopoly authorities. The author has formulated proposals for improving the legal regulation and practice of preventing violations of mandatory antitrust laws by the antimonopoly authorities.