| UDEAC | Economic and Monetary Community of Central Africa (now CEMAC) |
| UEMOA | West African Economic and Monetary Union |
| UIN | Unique Identifier Number |
| ULCC | Ultra large crude carrier |
| UMA | Arab Maghreb Union |
| UN | United Nations |
| UNAIDS | Joint United Nations Programme on HIV/AIDS |
| UNCITRAL | United Nations Commission on International Trade Law |
| UNCTAD | United Nations Conference on Trade and Development |
| UNCTC | United Nations Center on Transnational Corporations |
| UN/DESA/SD | United Nations Department of Economic and Social Affairs, Statistics Division |
| UNDP | United Nations Development Program |
| UNEP | United Nations Environment Program |
| UNESCO | United Nations Educational, Scientific, and Cultural Organization |
| UNICEF | United Nations Children Fund |
| UNIDO | United Nations Industrial Development Organization |
| UK | United Kingdom |
| UR | Uruguay Round |
| URAA | Uruguay Round Agreements Act |
| USAID | U.S. Agency for International Development |
| USF&CS | United States Foreign and Commercial Service |
| US | United States |
| USA | United States of America |
| USC | United States Code |
| USDA | United States Department of Agriculture |
| USDOC | United States Department of Commerce |
| USEC | United States Mission to European Communities |
| USITC | United States International Trade Commission |
| USOECD | United States Mission to the Organization for Economic Cooperation and Development |
| USP | United States Price |
| US-SACU FTA | US-Southern African Customs Union Free Trade Area |
| USTR | United States Trade Representative, or Office of the United States Trade Representative |
| USTTA | United States Travel and Tourism Administration, U.S. Department of Commerce |
| USUN | United States Mission to the United Nations |
