HSI
- Billboard Hot 100
- Croatian Syrmian Initiative
- Croatian World Games
- HS1 (disambiguation)
- HSI (track team)
- HSI color space
- Hang Seng Index
- Hastings Municipal Airport
- Heterosubtypic immunity
- High Speed Interconnect
- Hispanic-serving institution
- Homeland Security Investigations
- Horizontal shaft impactor
- Horizontal situation indicator
- Hsi (surname)
- Humane Society International
- Hurricane Severity Index
- Hyperspectral imaging
- Icelandic Handball Association
- Xi (disambiguation)