BSI
- BS (disambiguation)
- BS1 (disambiguation)
- BSI Group
- BSI Ltd
- BSI coupling
- Back-illuminated sensor
- Balesin Airport
- Bangunan Sultan Iskandar
- Bank Saderat Iran
- Bank Syariah Indonesia
- Bible Society of India
- Bloodstream infections
- Body substance isolation
- Botanical Survey of India
- British Society for Immunology
- Bureau of Special Investigation
- CBSI (disambiguation)
- Federal Office for Information Security
- KBSI (disambiguation)
- The Baker Street Irregulars
- WBSI (disambiguation)