| Harvard Alumni Association | Academic & Science |
| Harvard Athletic Association | Academic & Science |
| Hungarian Astronomical Association | Academic & Science |
| Hastings Architecture Associates | Academic & Science |
| Hillsboro Aero Academy | Academic & Science |
| Haloacedic Acid A | Academic & Science |
| Haloacetic Acid And | Academic & Science |
| Magyar Csillagászati Egyesület | Academic & Science |
| Magyar Csillag?zati Egyes?et | Academic & Science |
| Hasvik | Airport Code |
| Home Automation Association | Business |
| Haloacetic Acid | Chemistry |
| Histiocytosis Association of America | Community |
| Hinsdale Adventist Academy | Community |
| Hospice Association of America | Community |
| Hispanics Across America | Community |
| Harvard Athletic Associaton | Community |
| Houston Apartment Association | Community |
| Haunted Attraction Association | Community |
| Havyaka Association of Americas | Community |
| History of Art and Architecture | Community |
| Houston Apartment Association's | Community |
| Historic Action Adventure | Computing |
| Horror Action Adventure | Computing |
| Hsanz Anzsbt Asth | General |
| Houston Apartment | General |
| Hamilton Anderson Associates | General |
| Heterocyclic Aromatic Amines | General |
| Helicopter Alighting Area | General |
| Alif Atoll | General |
| Hungry After All | General |
| Historically Accurate Appearances | General |
| Hill Ascent Assist | General |
| Honda Access Asia | General |
| Hormonally Active Agent | General |
| Honda Access America | General |
| Historic Auto Attractions | General |
| Headrests Adjustable on All Seats | General |
| Height Above Airport | Governmental |
| Heavy Anti Archiver | Governmental |
| Houston Arts Alliance | Governmental |
| Home Acoustics Alliance | Governmental |
| HARWADA | Indian Railway Station |
| Hepatitis- Associated Antigen | Medical |
| Hepatitis Associated Antibodies | Medical |
| Health Action Area | Medical |
| Hospital Activity Analysis | Medical |
| Hepatitis-Associated Antibody | Medical |
| Heavy Anti-aircraft | Military and Defence |
| Hasvik, Norway | Regional |
| HAN: a language of the United States | Regional |
| Hepatitis Australian Antigen | Regional |
| Heure Avancée de l'Atlantique | Regional |
| Heure Avanc? de l'Atlantique | Regional |
| High Altitude Airship | Space Science |
| High Altitude Abort | Space Science |
| Hampton Athletic Association | Sports |
