The article presents aspects of the legal regulation of international scientific cooperation aimed at the creation and operation of unique scientific installations of the “megascience” class. On the example of scientific projects CERN, ITER and XFEL, the individual features of legal regulation are analyzed: the legal basis, the key provisions of the concluded international agreements, as well as the relationship with the Russian legislation. On the basis of the analysis and generalization, the authors identify the features of legal regulation, which should be taken into account when creating future scientific projects of the “megascience” class.