OSI

OSI may refer to:

Places

OSI Group, an American holding company of meat processors that service the retail and food service industries
OSI Pharmaceuticals, an American pharmaceutical company
OSI Restaurant Partners, the restaurant and entertainment group that includes Outback Steakhouse
OSI Systems, a company that manufactures security scanners and medical equipment based in California
Objective Systems Integrators, a company that provides monitoring software for communication networks
Open Systems International, an automation software vendor for the electric, petroleum, transportation and water industries
Officine Stampaggi Industriali, defunct Italian coachbuilder

Office of Scientific Intelligence, former name of a department of the Central Intelligence Agency now called the Directorate of Science and Technology
Office of Strategic Influence, a short-lived former American government agency created in 2001, part of the Department of Defense and focused on psychological warfare
Office of Special Investigations (disambiguation), a name shared by several government agencies
Office of Scientific Integrity, now United States Office of Research Integrity
Office of Special Investigation (Republic of Korea), a secret intelligence unit of Republic of Korea Air Force

Olomouc Summer Institute, an educational program for high-school students
Open Space Institute, an organization that seeks to preserve scenic, natural and historic landscapes
Open Society Institute, a private charitable foundation established by George Soros to promote open societies around the world
Ordnance Survey Ireland (Suirbhéireacht Ordanáis Éireann)
Otto-Suhr-Institut, the political-science institute of the Free University of Berlin

OSI, acronym for Official Sector Involvement in sovereign debt restructuring deals, as opposed to PSI (Private Sector Involvement).
Options Symbology Initiative, a plan to change the way that exchange-traded options are named

Open Systems Interconnection, (ISO 7498) a joint ISO and ITU-T standard for computer networks and communication protocols
- OSI model, a layered description for communications and computer network protocol design
- OSI protocols
Open Source Initiative, an organization dedicated to promoting open source software
Ohio Scientific Inc., a microcomputer manufacturer from the late 1970s to the early 1980s
Open Switching Interval, a type of disconnect supervision
On-Site Inspection, an advanced measure technique combining several methods - especially used in order to detect nuclear tests
Officine Stampaggi Industriali, Italian coachbuilder

OSI (band), an American progressive rock supergroup named after the former Office of Strategic Influence government agency
- Office of Strategic Influence (album), the 2003 debut album by the band OSI
Origin Systems, a former United States computer game developer
Orchestra della Svizzera Italiana, an orchestra in southern Switzerland in the city of Lugano which is in the canton of Ticino.

"Office of Scientific Intelligence", a fictional United States government agency in several television programs and movies
"Office of Secret Intelligence", a fictional United States government secret agency in the animated series The Venture Bros.