The creation of unique scientific facilities of the “Megascience” class is a very complex and lengthy organizational and technical process, for the implementation of which the resources of several states are usually involved. In connection with the participation in the creation and implementation of a scientific project of the “Megascience” class of several states, it becomes necessary to distribute the rights, duties, costs and powers of project management among the participants. Currently, the Russian Federation lacks a sufficient level of legal regulation of projects of the “Megascience” class. Based on the analysis of Russian and foreign experience in the implementation of scientific projects of the “Megascience” class, the article presents proposals for improving the legal regulation of these projects being implemented on the territory of the Russian Federation. The article also discusses the specific problems that one has to face when implementing projects of the “Megascience” class in Russia, and the ways to solve them. In addition, the authors’ definitions of such key terms as “Megascience” class project, “unique scientific facility of the “Megascience class” and “scientific collaboration,” which are absent in the current legislation, are proposed. This research was supported by the Russian Foundation for Basic Research (grant 18-29-15036mk “Models for legal regulation of unique scientific facilities of ‘Megascience’ class at the national and international levels in the context of technological development of the Russian Federation”).