DSI is an initialism for the following companies:
- Data Sciences International
- Dave Smith Instruments, an American synthesizer company
- DaySmart Software, Inc., a software company
- Deep Springs International
- Delphi Schools, Inc.
- Delphine Software International, a now bankrupt software company
- Destination Software, Inc., a video game company
- Distinctive Software, Inc., a former Canadian software house
- Diversified Specialty Institute Holdings, Inc., a US-based healthcare group
- DYWIDAG Systems International, an international supplier of ground anchors and post-tensioning systems
- State Hydraulic Works (Turkey) (Turkish: Devlet Su İşleri (DSİ)), a state agency in Turkey
DSI also represents the following institutions:
- Data Storage Institute, a Singaporean national research institute
- Department of Special Investigation, a Thai government organization for special investigation
- Deutsche Schule Istanbul, a private high school in Istanbul
- Dienst Speciale Interventies, a Dutch government organization for counter-terrorism actions
DSI can also mean:
- Data storage interrupt, the name used for a segmentation fault on PowerPC-based processors
- Data Stream Interface, computer network protocol to run Apple Filing Protocol over TCP
- Dead Space Ignition, a video game midquel to the Dead Space series
- Death or serious injury
- Delay slot instruction, a term from computer architecture
- Depolarization-induced suppression of inhibition, a type of modulation of inhibitory neurotransmission
- Detective Superintendent, a kind of British police's superintendent rank
- Deutsches SOFIA Institut, an institute helping develop SOFIA
- Diffused Surface Illumination, a multi-touch technique using a special acrylic Endlighten that disperses even light supplied by edge lighting the acrylic.
- Diffusion Spectrum Imaging, a brain scanning method used in MRI Tractography to identify crossing fibers in neural tissue
- Digital Signal Interface, a protocol for controlling of lighting in buildings
- Disparity Space Image, a data structure used in computer stereo vision
- Display Serial Interface, a serial protocol for mobile display devices
- Diverterless supersonic inlet, a type of jet engine air intake
- Docking Score Index, a drug testing method
- DontStayIn, a social networking website
- Dope Stars Inc., an industrial metal band formed in 2002
- Nintendo DSi, Nintendo's third iteration of the Nintendo DS handheld video-game console