HRT
- Feminizing hormone therapy
- Gender-affirming hormone therapy
- HRT Formula 1 Team
- Habit reversal training
- Hampton Roads Transit
- Hard real-time
- Hartwell Railroad
- Haupt Racing Team
- Heart rate turbulence
- Heavy rail transit
- Helsinki Regional Transport Authority
- Hertfordshire
- Hertfordshire Rail Tours
- High rising terminal
- Hiroshima Rapid Transit
- Hormone replacement therapy
- Hostage Rescue Team
- Hrvatska radiotelevizija
- Hudson River Trading
- Humane Research Trust
- Hurlburt Field
- Hydraulic retention time
- Hértevin language
- Masculinizing hormone therapy
- RAF Linton-on-Ouse
- Skyline (Honolulu)
- Walkinshaw TWG Racing