MCI

MCI may refer to:

• 1101 in Roman numerals
• mCi, millicurie, 1/1000 of a curie, a non-SI unit of radioactivity
• MCi, megacurie, 1,000,000 times a curie

Company

• MCI Inc., a former American telecommunications company now acquired by Verizon Communications
• MCI Communications, originally Microwave Communications Inc., the corporation that operated as MCI from 1963–1998
• MCI Group Holding SA, event, communication and association management company
• Motor Coach Industries, a coach/bus manufacturing company
• Music Center Incorporated, later known as Music Consultants Incorporated, a company that manufactured multi-track audiotape recorders and mixing consoles for professional studio recording

Institute

• Maine Central Institute, a boarding school in Maine, founded in 1866
• Marine Corps Institute, a coursework of Marine Corps education and training programs
• Martingrove Collegiate Institute, a secondary school located in Toronto, Ontario
• Medical Council of India
• Mennonite Collegiate Institute, a private, religious school in the town of Gretna, in Southern Manitoba
• Museum Conservation Institute, of the Smithsonian Institution

University

• MCI Management Center Innsbruck, a university located in Innsbruck, Austria

Health and Science

• Medical Council of India
• Mild cognitive impairment, a neurological affliction often associated with Alzheimer's disease
• Mass casualty incident, a medical emergency involving more patients than can be easily handled by the crews initially assigned to the incident
• Magnetic current imaging using a scanning SQUID microscope
• Myocardial infarction
• Modulation contrast imaging, is term in optical imaging

Computer

• Media Control Interface/Multimedia Control Interface, an API for controlling multimedia peripherals connected to a Microsoft Windows or OS/2 computer

Other

• Meal, Combat, Individual, the successor to the US Army C-ration
• Monetary conditions index, a macroeconomic index number relevant for monetary policy.
• Malicious caller identification, a type of enhanced telephone service
• Macroinvertebrate community index, a measure used in New Zealand for the environmental status of streams
• Miss Chinese International Pageant, an annual pageant where International women of Chinese descent compete for the crown of Miss Chinese International
• MCI, The IATA airport code for the Kansas City International Airport in Kansas City, Missouri, US
• Michigan City (Amtrak station), Indiana, United States; Amtrak station code MCI
• Motion clarity index, dimensionless value which describes the quality of LCD to show a moving picture