MEI may refer to: Education MEI Academy, an international school Mathematics in Education and Industry, an examination board affiliated with the OCR examination board Mennonite Educational Institute, an independent grades K-12 school in Abbotsford, British Columbia Businesses MEI (company), manufacturer of cash handling systems Matsushita Electric Industrial Co., Ltd. Micro Electronics, Inc. Member of the Energy Institute (MEI) , an annual conference of Italian independent record labels Government Ministry of Economy and Innovation (), the Portuguese economy ministry Middle East Institute Marginal efficiency of investment or internal rate of return, a relationship between interest rate and amount of investment that can be profitable at a given time Meridian Regional Airport Montreal Economic Institute Meridian (Amtrak station), Amtrak station code MEI, Mississippi, United States Medicare Economic Index Military MEI Hellhound (Grenade), low velocity multipurpose grenade MEI Mercury, a family of grenades developed by Martin Electronics, Inc. Science Iodomethane (methyl iodide, MeI), a halomethane Multivariate ENSO index 4-Methylimidazole (4-MEI), a chemical compound Technology Management Engine Interface, a component of Intel Active Management Technology Music Encoding Initiative, a music encoding format Other uses Media and Entertainment International, a former global union federation OECD Main Economic Indicators, a monthly publication of the Organisation for Economic Co-operation and Development See also Mei (disambiguation)