ISTC may refer to:

• Illinois Sustainable Technology Center housed at the Prairie Research Institute
• Incunabula Short Title Catalogue
• Independent Sector Treatment Centre, part of the UK National Health Service
• Institute of Scientific and Technical Communicators
• International Science and Technology Center
• International Space Training Center, the fictional institution behind Mission: Space ride at Epcot
• International Standard Text Code, a numeric code in development by the ISO for textual works
• International Student Travel Confederation
• The former Iron and Steel Trades Confederation trade union, now part of Community (trade union)