| ISTA | Idaho Science Teachers Association 
| Others |
| ISTA | Illinois Science Teachers Association
| Others |
| ISTA | Illinois Soil Testing Association
| Others |
| ISTA | Indiana State Teachers Association
| Others |
| ISTA | Information Science and Technology Abstracts
| Others |
| ISTA | Institute Of Space Technology And Aeronautics
| Others |
| ISTA | Integrated Service Technical Application
| Others |
| ISTA | International Safe Transit Association
| Others |
| ISTA | International School of Temple Arts
| Others |
| ISTA | International Schools Theatre Association
| Others |
| ISTA | International Schools Theatrical Arts
| Others |
| ISTA | International Security Training Academy
| Others |
| ISTA | International Seed Testing Association
| Others |
| ISTA | International Selling And Trade Association
| Others |
| ISTA | International Soccer Training Academy
| Others |
| ISTA | International Society for Technology in Arthroplasty
| Others |
| ISTA | International Sound Therapy Association
| Others |
| ISTA | International Strength Training Association
| Others |
| ISTA | International Syclone Typhoon Association
| Others |
| ISTA | Intertank Structural Test Assembly
| Others |
| ISTA | Irish Science Teachers' Association
| Others |
| ISTA | Iterative Soft Thresholding Algorithm
| Others |