IHS may refer to:
- A common Christogram based on the first three letters of "Jesus" in Greek (Ίησους, in Greek capitals ΙΗΣΟΥΣ, or ΙΗϹΟΥϹ using lunate sigmas, semi-Latinized IHSOVS).
- Abbreviation for the In hoc signo vinces legend.
- IBM HTTP Server
- Ice Hockey Superleague
- IHS Press, a Catholic publishing house based in Virginia
- IHS Inc. (Information Handling Services), an energy and engineering consulting firm
- Illinois Humane Society
- Indian Health Service, a division of the United States Department of Health and Human Services
- Indiana Historical Society
- Integrated heat spreader, a copper covering on top of some computer processors
- Institute for Humane Studies
- the British Integrated Household Survey
- International Headache Society
- Integrated Health Services, Pakistan
- Institute for Humanist Studies
- Interstate Highway System
- International Horn Society
- IHS, the health care division of Dictaphone
- Intensity, hue, saturation; a synonym for the HSL color space
- Ipswich Historical Society
- Ironclads: High Seas, a steam-ship period tactical naval simulator
High schools
- Independence High School (disambiguation) – multiple schools
- International High School (disambiguation) – multiple schools
- Irvington High School (disambiguation) – multiple schools
- Ithaca High School (disambiguation) – multiple schools
- Indian High School - Dubai, United Arab Emirates
- Inglemoor High School – Kenmore, Washington, US
- Interboro High School – Prospect Park, Pennsylvania, US
- Interlachen High School – Interlachen, Florida, US
- Interlake High School – Bellevue, Washington, US
- Inverkeithing High School – Inverkeithing, Fife, Scotland
- Irondale High School – New Brighton, Minnesota, US
- Irondequoit High School - Irondequoit, New York, US
- Ironton High School – Ironton, Ohio, US
- Ironwood High School – Glendale, Arizona, US
- Irvine High School – Irvine, California, US
- Isabella High School - Maplesville, Alabama, US
- Ishpeming High School - Ishpeming, Michigan, US
- Issaquah High School – Issaquah, Washington, US
- Island High School – Alameda, California, US