Summary: U.S. currency, reportedly the most widely held in the world, is susceptible to counterfeiting. The Federal Reserve estimates that of the $380 billion of U.S. currency in circulation, more than 60 percent may be held outside the United States. The widespread use of U.S. currency abroad, together with the outdated security features of the currency, make it particularly vulnerable to international counterfeiters. Widespread counterfeiting of U.S. currency could undermine confidence in the dollar and, if done on a large enough scale, could harm the U.S. economy. This report discusses (1) the nature of counterfeiting of U.S. currency abroad, (2) the extent of that counterfeiting and of concerns about this issue, and (3) the status of U.S. efforts to deter such counterfeiting. GAO summarized this report in testimony before Congress; see: Counterfeit U.S. Currency Abroad: Observations on Counterfeiting and U.S. Deterrence Efforts, by JayEtta Z. Hecker, Associate Director for International Relations and Trade Issues, before the Subcommittee on General Oversight and Investigations, House Committee on Banking and Financial Services. GAO/T-GGD-96-82, Feb. 27 (21 pages).