INTRODUCTION. The article analyses the sources of international law, national legislation of the Russian Federation, as well as that of certain foreign States regulating the operation of private military and security companies (PMSCs) in armed conflict. The article highlights the out-comes of the work of the UN Special Rapporteurs and Working Groups to study the activity of PMSCs and the impact it had on the observance of human rights. The authors further analyze the status of PMSC personnel under international humanitarian law. The article also looks at the positions expressed by the delegations of Member States during the discussion of the 2010 Draft Convention on Private Military and Security Companies (PMSCs) and provides recommendations for developing an appropriate international regulatory framework. The authors also examined State practice of the implementation of the The Montreux Document on Pertinent International Legal Obligations and Good Practices for Statesт Related to Operations of Private Military and Security Companies During Armed Conflict related to the operation of private military and security companies during armed conflict.MATERIALS AND METHODS. The article contains an analysis of the main sources of international law, the documents drafted by the United Nations International Law Commission, special rapporteurs and working groups on the matter, and State practice. It also addresses Russian and foreign legal scholarship. From a methodological perspective, this study relied on the general scientific (analysis, synthesis, systemic approach) and private legal methods of knowledge (formal-legal, comparative legal studies).RESEARCH RESULTS. Based on the study, it is argued that an international treaty should be adopted to regulate the activities of PMSCs, which would establish mechanisms to monitor and hold PMSCs and their employees legally accountable.