BMI may refer to:

In business:

• BMI (airline), British Midland International, an airline of the United Kingdom
• bmi baby, another UK airline, a low-cost subsidiary of BMI
• BMI Healthcare, a British healthcare company
• Baltimore Museum of Industry
• Bank Melli Iran, the first national Iranian bank
• Best Motoring International, a Japanese magazine and video series for automobiles and racing
• Birmingham and Midland Institute, England; not to be confused with the Birmingham Medical Institute, England.
• Broadcast Music, Inc., a collecting society for composers' copyrights
• Business model innovation
• Central Illinois Regional Airport, IATA code BMI

Other uses:

• Biculculline methiodide, a GABA-A antagonist used in neuroscience research
• Big Mac Index, a measurement of purchasing power parity across different countries, popularized by The Economist
• Body mass index, a numerical computation regarding height and weight
• Brain Machine Interface, a technological interface between a brain and an artificial device
• Bundesministerium des Innern, the Federal Ministry of the Interior (Germany)
• Bureau of Military Information of the Union Army
• Business Management Intelligence, a product of Urban Science