| Innovative Structures Group | Academic & Science |
| Integrated Starter Generator | Academic & Science |
| Idle Stop & Go | Academic & Science |
| Ishigaki | Airport Code |
| Innovated Sports Group | Business |
| Intermarket Surveillance Group | Business |
| Industry Specific Group | Business |
| International Sommelier Guild | Business |
| Insurance Specialty Group | Business |
| Investor Stewardship Group | Business |
| iShares MSCI Singapore | Business |
| Interior Serv. | Business |
| Innovative Strategic Growth | Business |
| Innocent Sinners Guild | Community |
| International School of Gemology | Community |
| Infinite Sword Glitch | Computing |
| Information Services Group | Computing |
| Information Storage Group | Computing |
| Intelligent Services Gateway | Computing |
| Internet Services Group | Computing |
| Internet Safety Group | Computing |
| Information Security Group | Computing |
| Inverse Signal Generator | Electronics |
| International Steel Group | General |
| Iraq Survey Group | General |
| Information Systems Group | General |
| International Sales Group | General |
| Inane Strategy Guessw | General |
| Industry Specification Group | General |
| Information Specialists Group | General |
| Integrity Staffing Group | General |
| Integrated Solutions Group | General |
| Integrated Security Group | General |
| Interim Staff Guidance | General |
| International Solutions Group | General |
| Insulated Shell Garment | General |
| Intelligent Stop And Go | General |
| Intelligent Service Gateway | General |
| Insolvency Services Group | General |
| Industrial Stakeholders Group | General |
| Information Sytem Generator | General |
| Inspire Share Give | General |
| Insight Sourcing Group | General |
| Interservice Steering Group | General |
| Intake Sound Generator | General |
| In Sixth Gear | General |
| Isuzu Suppliers Group | General |
| Imperial System Guard | General |
| Iraq Search Group | General |
| Invicible Sword Goddess | General |
| Individual Salary Gap | General |
| Iraq Study Group | General |
| Interpreting Stakeholder Group | General |
| Identification Systems Group | General |
| Institute for Security Governance | Governmental |
| Illinois Student Government | Governmental |
| Islamic Society of Germantown | International |
| International Support Group | International |
| International Society for Gerontechnology | International |
| Internet Scrubbing Gateway | Internet |
| Indian Snake Giver | Jobs |
| Independent Scientific Group (advises government on the control of tuberculosis in cattle in the UK) | Medical |
| Institute for Systems Genomics | Medical |
| Information Synchronization Group | Military and Defence |
| Iraqi Survey Group | Military and Defence |
| ISG Railways | Regional |
| Istp Scheduling Group | Space Science |
| Innovative Sports Group | Sports |
| Innovative Sport Group | Sports |
