HTH may stand for:
- hand-to-hand or mêlée combat
- Heavy Transport Helicopter is a program study into the European Heavy Lift Helicopter Program by Eurocopter
- Helix-turn-helix, in proteins, a major structural motif capable of binding DNA
- Gary and Jerri-Ann Jacobs High Tech High Charter School, a public charter high school in San Diego, USA
- High-Test Hypochlorite, typically sodium or calcium hypochlorite, a strong chlorinating agent used for swimming pools and water wells
- Highway to Hell, a 1979 album by AC/DC
- Highway to Hell (song)
- Hilltop Hoods, an Australian hip hop group
- Hollywood Tower Hotel, a fictional location featured in the Tower of Terror rides
- Hometown Heroes
- Hewitt Trussville High
- Internet slang for "Hope This/That Helps", "Happy To Help", "Hit The Hay", "How The Hell?", "Heart To Heart", or "Hand To Hand"