| International Theatrical Truss Corporation | Business |
| International Technology Transfer Conference | Business |
| International Towing Tank Conference | Community |
| Internationale Trekker Trek Club | Community |
| Institute for Tourism Travel and Culture | Community |
| International Travel and Trailer Clubs | Community |
| Innovation Technology training center | Computing |
| Iowa Telecommunications and Technology Commission | Computing |
| Information Technology Training Centre | Computing |
| Informaciniu technologiju taikymo centras | General |
| Informacinių technologijų taikymo centras | General |
| Integrative Trauma Treatment Center | General |
| International Teaching and Training Centre | General |
| International Team Training Center | General |
| Industrial Transformation Training Centres | General |
| Instituto Terra Trabalho Cidadania | General |
| Imagery To The Crowd | General |
| Integrated Train Testing Centre | General |
| Institute for Training and Technical Cooperation | Governmental |
| International Tropical Timber Council | Governmental |
| Institute for Training and Technical | Governmental |
| Intermodal Transportation Technical Committee | Governmental |
| Italian Tools Technology Company | International |
| International Teacher and Training Centre | International |
| International Trenchless Technology Conference | International |
| Immune Transplant and Therapy Center | Medical |
| Information Technology Training Center | Technology |
| Information and Telecommunication Technology Center | Telecommunication |
