SMI may refer to:
Business:
- Supplier Managed Inventory, a business model
- Swiss Market Index, Switzerland's blue-chip index
Companies:
- Shepardson Microsystems, which produced OSs and programming languages for the Atari 8-bit and Apple II
- Speedway Motorsports, Inc., which owns and operates numerous American NASCAR racetracks
- Sun Microsystems, Inc., pioneer computer manufacturer acquired by Oracle Corporation in 2010
Computer industry:
- The file extension for SAMI, for subtitles and captions
- Self mounting image, a disc image encapsulated in an application that mounts it as a file system
- Structure of Management Information, a subset of Abstract Syntax Notation One used in Simple Network Management Protocol
- The three letter (Microsoft) file extension for Synchronized Multimedia Integration Language, used in multimedia presentation delivery
- SMI – system management interrupt, see System Management Mode
- Serial Management Interface, an interface to configure an Ethernet PHY.
Physics:
- Spatially Modulated Illumination, a super resolution microscopy method Vertico SMI
Medicine:
- Serious Mental Illness
- Swedish Institute for Infectious Disease Control
- SMI 049, a drug resistant type of tuberculosis named after SMI
Other:
- The Secret of Monkey Island, a computer game
- Seneca Meadows, Inc., New York State's largest landfill
- Sergeant Major Instructor, a warrant officer appointment in the British Army
- Sports Management International, a fictional sports agency in the film Jerry Maguire
- St. Michael's Institution, a prominent school in Malaysia
- Storage Management Initiative - Specification (SMI-S), developed by the Storage Networking Industry Association
- SMI, the IATA airport code for Samos International Airport in Greece