| MAC | Market Access and Compliance Unit, U.S. Department of Commerce |
| MAI | Multilateral Agreement on Investment |
| MDB | Multilateral development bank |
| MDG | Millennium Development Goal(s) |
| MEAs | Multilateral Environmental Agreements |
| MERCOSUR | Mercado Común del Sur (Southern Common Market) |
| MFA | Multi-Fiber Arrangement |
| MFN | Most-Favored Nation |
| MIF | Multilateral Investment Fund |
| MIGA | Multilateral Investment Guarantee Agency |
| MITI | Ministry of International Trade and Industry (Japan) |
| MNA | Middle East and North Africa Region (World Bank) |
| MNC | Multinational Corporation |
| MOFERT | Ministry of Foreign Economic Relations and Trade (People’s Republic of China) |
| MOSS | Market-oriented sector-specific negotiation process (United States-Japan) |
| MOU | Memorandum of Understanding |
| MPT | Ministry of Posts and Telecommunications |
| MRA | Mutual Recognition Agreement |
| MRU | Mano River Union |
| MSA | Multilateral Steel Agreement |
| MSG | Melanesia Spearhead Group |
| MT | Metric Ton |
| MTN | Multilateral Trade Negotiations |
| MTO | Multilateral Trade Organization |
| MTS | Multilateral Trading System |
