| HART | Had Any Rice Today 
| Others |
| HART | Halt All Racist Tours
| Others |
| HART | Happy Atari Rotating Thing
| Others |
| HART | Harm Assessment Risk Tool
| Others |
| HART | Hazardous Area Response Team
| Others |
| HART | HEALING and RESTORING TOGETHER
| Others |
| HART | Healthy Access To Real Treatment
| Others |
| HART | Heart Attack Rescue Training
| Others |
| HART | Heart Avoiding Radiation Therapy
| Others |
| HART | Heterogeneous Aerial Reconnaissance Team
| Others |
| HART | High Acuity Response Team
| Others |
| HART | High Angle Rifle Training
| Others |
| HART | Highway Accessible Remote Transducer
| Others |
| HART | Highway Addressable Remote Transducer
| Others |
| HART | Highway Addressable Remote Transmitter
| Others |
| HART | Hillsboro Artists' Regional Theatre
| Others |
| HART | Hillsborough Area Regional Transit
| Others |
| HART | HIV Assisted Reproduction Treatment
| Others |
| HART | HIV Assisted Reproductive Technologies
| Others |
| HART | Hofstra Alumni Recruitment Team
| Others |
| HART | Homeless Animal Rescue Team
| Others |
| HART | Honda of America Race Team
| Others |
| HART | Honda of America Racing Team
| Others |
| HART | Honolulu Authority for Rapid Transportation
| Others |
| HART | Hornet Autonomous Real Time
| Others |
| HART | Horrible Artistic Ridiculous Teen
| Others |
| HART | Housatonic Area Regional Transit
| Others |
| HART | Housing Access Resource Team
| Others |
| HART | Housing Action Resource Trust
| Others |
| HART | Houston Animal Rights Team
| Others |
| HART | Human Assisted Reproductive Technology
| Others |
| HART | Huntington Area Rapid Transit
| Others |
| HART | Hypervelocity Aircraft Rocket, Tactical
| Others |