Most liquidity-providing operations of the European Central Bank (ECB) have been conducted through variable-rate tenders. However, fixed rates were first employed in the main refinancing operations (MROs) and are still used in other liquidity management operations. In October 2008, the ECB decided to carry MROs again at a fixed rate. In a simple threestage game in which banks can obtain liquidity through the open-market operations of the ECB, through interbank transactions, or through “standing facilities,” this paper revisits the dilemma between fixed- and variable-rate procedures, with an emphasis on the scenarios that are particularly relevant under the recent credit crisis, namely collateral shortage, rationing in the interbank market, and non-acute estimation by the ECB of the system’s liquidity needs.