| ISSR | Ice Super Star Racing 
| Others |
| ISSR | Inaccessible State Space Removal
| Others |
| ISSR | Incremental Software Specification Review
| Others |
| ISSR | Independent Secondary Surveillance Radar
| Others |
| ISSR | Indian Society for Sleep Research
| Others |
| ISSR | Individual Standard Status Report
| Others |
| ISSR | Infrastructure System and Services Research
| Others |
| ISSR | Inland Sea Shorebird Reserve
| Others |
| ISSR | Institute For Social Science Research
| Others |
| ISSR | Institute for Social Sciences Research
| Others |
| ISSR | Institute of Statistical Studies and Research
| Others |
| ISSR | Intelligence Specialist Seaman Recruit
| Others |
| ISSR | Inter Simple Sequence Repeat
| Others |
| ISSR | Inter Simple Sequence Repeats
| Others |
| ISSR | Inter-Simple Sequence Repeat
| Others |
| ISSR | International School of the Stockholm Region
| Others |
| ISSR | International Shiloh Shepherd Registry
| Others |
| ISSR | International Social Science Review
| Others |
| ISSR | International Society for Science and Religion
| Others |
| ISSR | International Society for Science Religion
| Others |
| ISSR | International Society for Serotonin Research
| Others |
| ISSR | International Society for the Sociology of Religion
| Others |
| ISSR | International Student Support Room
| Others |
| ISSR | ISS Rail
| Others |
| ISSR | ISS Rail Incorporated
| Others |