MCI

MCI or mci may refer to:

Organizations

MCI Communications, originally Microwave Communications Inc., a corporation that operated as MCI from 1963 to 1998
- MCI Inc., formerly called WorldCom, which acquired MCI Communications, and was later acquired by Verizon Communications
MCI (recording studio gear), a manufacturer of multi-track audio tape recorders and mixing consoles for professional studio recording (officially Music Center Incorporated, later Music Consultants Incorporated)
Mobile Telecommunication Company of Iran, the largest mobile phone operator in Iran
Motor Coach Industries, a coach/bus manufacturing company
Music Collection International, the music division of Video Collection International
MCI, Frank Farian's record label

Maine Central Institute, a boarding school in Maine, United States
Malvern Collegiate Institute, a secondary school in Toronto, Ontario, Canada
Marine Corps Institute, a coursework of Marine Corps education and training programs
Martingrove Collegiate Institute, a secondary school in Toronto, Ontario, Canada
MCI Management Center Innsbruck, a privately organized business school in Innsbruck, Austria
Medical Council of India, a former statutory body for establishing uniform and high standards of medical education in India
Mennonite Collegiate Institute, a private religious school in Gretna, Southern Manitoba
Middlefield Collegiate Institute, a secondary school in Markham, Ontario, Canada
Museum Conservation Institute, of the Smithsonian Institution

Ministry of Communications and Information, a ministry of the Government of Singapore
Motek Cultural Initiative, a Toronto-based nonprofit organization promoting Israeli music and culture

Millicurie (mCi), 1/1000 of a curie, a non-SI unit of radioactivity
Megacurie (MCi), 1,000,000 times a curie, a non-SI unit of radioactivity
Macroinvertebrate Community Index, an index where the presence or lack of macroinvertebrates is used for monitoring stream health in New Zealand
Magnetic current imaging, using a scanning SQUID microscope
Malicious caller identification, a type of enhanced telephone service
Mass-casualty incident, a medical emergency involving more patients than can be easily handled by the crews initially assigned to the incident
Media Control Interface, an API for controlling multimedia peripherals connected to a Microsoft Windows or OS/2 computer
Meta-circular evaluator, in computing
Methylchloroisothiazolinone, in chemistry
Mild cognitive impairment, a neurological affliction often associated with Alzheimer's disease
Modulation contrast imaging, a term related to optical transfer function

1101, in Roman numerals
Kansas City International Airport (IATA code), Missouri, United States
Meal, Combat, Individual ration, the successor to the U.S. Army C-ration
Michigan City station (Amtrak code), Indiana, United States
Miss Chinese International Pageant, an annual pageant for international women of Chinese descent
Monetary conditions index, a macroeconomic index number relevant for monetary policy
Manchester City F.C., abbreviated as MCI
Mese language, an ISO 639-3 code
Missing Children Incident, an event in the lore of Five Nights At Freddy's