ISAS may refer to:
- International School for Advanced Studies, a post-graduate teaching and research institute in Trieste, Italy
- Institute of Space and Astronautical Science, a Japanese research institute currently part of the Japan Aerospace Exploration Agency
- Independent Schools Association of the Southwest, an association of 89 independent schools located in Arizona, Kansas, Louisiana, New Mexico, Oklahoma, and Texas.
- Ictal-Interictal SPECT Analysis by SPM, a method of localizing seizures
<!-- * International Society of Anglo-Saxonists, an organization open to all persons interested in any aspect of the culture of Anglo-Saxon England, 450-1066 AD. http://www.isas.us -->
<!-- * International Standardization and Accreditation Services, New York, http://www.isas.org -->
<!-- * Idaho Science and Aerospace Scholars, http://www.sde.idaho.gov/academic/isas/ -->
