The Unified Energy System (OAO RAO UES of Russia; Russian: ЕЭС России or Russian: Единая Энергетическая Система) was an electric power holding company in Russia. It controlled about 70% of Russia's installed electric capacity, 96% of its high-voltage grid and over 70% of its transmission lines. In addition to the Russian market, RAO UES exported electricity to Scandinavia and to other members of the CIS. The last head of RAO UES was Anatoly Chubais.

Unified Energy System of Russia was established by Presidential Decree #932, signed on August 15, 1992, as an electric energy holding company. Most of the state-owned electric energy assets, such as thermal and hydroelectric power plants, transmission lines, state-owned shares in power, research & engineering, and construction companies were transferred to RAO UES, with the exception of any assets related to nuclear energy. In total, RAO UES owned more than 70 of the energy companies and more than 40 of the power plants with federal-level importance. It also owned the transmission system operator, Federal Grid Company, (or, RAO FGC, the current successor of RAO UES and the operator of Russia's wide area transmission network) and the system operator of the Centralized Dispatching Administration (OAO SO-CDA). The first head of the company was Anatoly Dyakov, who held the positions of President and Chairman of the Directors Council.