| National Institute for Chemical Studies | Academic & Science |
| National Institute for Computational Sciences | Academic & Science |
| Nucleus independent chemical shifts | Academic & Science |
| Newhouse Internet and Computing Services | Business |
| Nature's International Certification Services | Business |
| Network Integration Consulting Services | Business |
| Nucleus Independent Chemical Shift | Chemistry |
| Network of International Christian Schools | Community |
| North Idaho Christian School | Community |
| Network Initiative for Conservation Science | Community |
| Norfolk Island Central School | Community |
| National Institute of Crop Science | General |
| Newborn Intensive Care Specialist | General |
| Newborn Intensive Care Specialists | General |
| National Intensive Care Surveillance | General |
| National Immunisation Coverage Survey | General |
| Nissan Induction Control System | General |
| NAS (National Airspace System) Interfacility Communications System | Governmental |
| National Instant Check System | Governmental |
| National Instant Criminal Background Check System | Governmental |
| Northwest Intertribal Court System | Governmental |
| Nice Institute for Competitive Studies | Governmental |
| National Instant Criminal Search | Governmental |
| National Institute of Clinical Studies | Medical |
| Neuro-Immuno-Cutaneous System | Medical |
| Neurological Impulse Combat System | Military and Defence |
| Nato Integrated Communications System | Military and Defence |
| Network Integrated Computing Solution | Networking |
| Novell Internet Caching System | Networking |
| Network Interface Cards | Networking |
| Newly Industrializing Countries States | Regional |
| Northern Ireland Civil Service | Sports |
