GSI may refer to:

Science and technology

* Geological Strength Index * Gonadosomatic Index * UK Government Secure Intranet * Grid Security Infrastructure, a computer networking specification

Businesses and organizations

Businesses

* Gemological Science International, gemstone identification/grading/appraisal services * Geophysical Service Incorporated, an American petroleum exploration corporation * Guangzhou Shipyard International, a Chinese state-owned shipbuilder * GSI Commerce, now eBay Enterprise, an American e-commerce company

Scientific organizations

* GSI Helmholtz Centre for Heavy Ion Research, Germany * Geographical Society of Ireland * Geospatial Information Authority of Japan * Geological Survey of India * Geological Survey of Ireland

Other organizations

* ''Gabinete de Segurança Institucional da presidência da república'' (Institutional Security Cabinet), Brazil * Gustav Stresemann Institute, a German educational charity

Other uses

* Graduate student instructor, a Teaching fellow#United States, teaching fellow at some US universities * Grand-Santi Airport, French Guiana (IATA code GSI) {{disambiguation