Mandatory reserve requirements are traditionally examined as monetary policy instruments through which central banks regulate banking liquidity, credit creation, and short-term interest rates. Their private-law status, however, remains comparatively underexplored. This article examines the legal nature of mandatory reserves maintained by banks with the Central Bank of the Republic of Uzbekistan and evaluates whether such reserves may be classified as a security instrument. The research applies doctrinal, functional, and comparative legal methods. Uzbekistan’s regulatory framework is compared with the minimum reserve system of the Eurosystem and the zero-reserve-requirement model currently used in the United States. The analysis demonstrates that the mandatory reserve mechanism in Uzbekistan possesses several security-like characteristics: compulsory segregation, restriction of disposition, immunity from enforcement, continued operation during bank rehabilitation and insolvency procedures, and potential use in liquidation. Nevertheless, it lacks the constituent features of a conventional pledge, trust, guarantee, deposit insurance arrangement, or other civil-law security interest.