| International Journal of Testing | International Journal of the Platonic Tradition | International Journal of Toxicology |
| International Journal of Turkish Studies | International journal of Turkish studies | International Ju-Jitsu Federation |
| International Judo Federation | International Jugglers' Association | International Jugglers’ Association |
| International Junior Science Olympiad | International Justice Mission | International Karate |
| International Karate + | International Karate Plus | International Kendo Federation |
| International Klein Blue | International Korfball Federation | International Krav Maga Federation |
| International Labor Organisation | International Laboratory Accreditation Cooperation | International Labour Office |
| International Labour Organization | International Lacrosse Federation | International Lamp Coding System |
| International Language and Law Association | International Laser Display Association | International Laser Ranging Service |
| International law | International Law Association | International Law Commission |
| International Lawn Tennis Challenge | International Lawn Tennis Challenge 1900 | International Lawn Tennis Challenge 1902 |
| International Lawn Tennis Challenge 1903 | International Lawn Tennis Challenge 1904 | International Lawn Tennis Challenge 1905 |
| International Lawn Tennis Challenge 1906 | International Lawn Tennis Challenge 1907 | International Lawn Tennis Challenge 1908 |
| International Lawn Tennis Challenge 1909 | International Lawn Tennis Challenge 1911 | International Lawn Tennis Challenge 1912 |
| International Lawn Tennis Challenge 1913 | International Lawn Tennis Challenge 1914 | International Lawn Tennis Challenge 1919 |
| International Lawn Tennis Challenge 1920 | International Lawn Tennis Challenge 1921 | International Lawn Tennis Challenge 1922 |
| International Lawn Tennis Challenge 1923 | International Lawn Tennis Challenge 1924 | International Lawn Tennis Challenge 1925 |
| International Lawn Tennis Challenge 1926 | International Lawn Tennis Challenge 1927 | International Lawn Tennis Challenge 1928 |
| International Lawn Tennis Challenge 1929 | International Lawn Tennis Challenge 1930 | International Lawn Tennis Challenge 1931 |
| International Lawn Tennis Challenge 1932 | International Lawn Tennis Challenge 1933 | International Lawn Tennis Challenge 1934 |
| International Lawn Tennis Challenge 1935 | International Lawn Tennis Challenge 1936 | International Lawn Tennis Challenge 1937 |
| International Lawn Tennis Challenge 1938 | International Lawn Tennis Challenge 1939 | International Lawn Tennis Federation |
| International League | International League Against Epilepsy | International League for Human Rights |
| International League of Antiquarian Booksellers | International Lease Finance Corporation | International Legal English Certificate |
| International Lesbian And Gay Association | International lesbian and gay association | International Lesbian and Gay Association |
| International Lesbian and Gay Law Association | International Lesbian, Gay, Bisexual, Trans and Intersex Association | International Lesbian, Gay, Bisexual, Transgender & Intersex Law Association |
| International Lesbian, Gay, Bisexual, Transgender and Intersex Law Association | International Liaison Committee on Resuscitation | International Libertarian Solidarity |
| International Library of Psychology, Philosophy and Scientific Method | International Life Saving Federation | International Lifeboat Federation |
| International Light Art Award | International Lighthouse and Lightship Weekend | International Linear Collider |
| International Livestock Research Institute | International Load Line Convention | International Longevity Alliance |
| International Love | International LT-Serie | International Magicians Society |
| International Maize and Wheat Improvement Center | International Management | International Management Group |
| International Manufacturing Technology Show | International Map of the World | International Marine Certification Institute |
| International Maritime Bureau | International Maritime Code for Dangerous Goods | International Maritime College Oman |
| International Maritime Confederation | International Maritime Dangerous Goods (IMDG) Code | International Maritime Dangerous Goods Code |
| International Maritime Employers Committee | International Maritime Organisation | International Maritime Organization |
| International Maritime Prize | International Maritime Rescue Federation | International Martial Arts Federation |
| International Master of Business Administration | International Masters | International Masters (Ringtennis) 2002 |
| International Masters (Ringtennis) 2004 | International Masters 1982 | International Masters 1983 |
| International Masters 1984 | International Masters Games Association | International Masters Ringtennis 2002 |
| International Masters Ringtennis 2004 | International Mathematical Union | International Max Planck Research School |
| International Max Planck Research School for Organismal Biology | International Max Rostal Competition | International Maxibasketball Federation |
| International MaxxPro | International Medal for Outstanding Discoveries in Mathematics | International Media Festival for Prevention |
| International Medical Informatics Association | International Medical University | International Medieval Congress |
| International Men's Day | International Men's Tennis Challenger 2017 | International Men's Tennis Challenger 2019 |
| International Men’s Day | International Men’s Tennis Challenger 2017 | International Men’s Tennis Challenger 2019 |
| International Mercantile Marine Company | International Merchandise Trade Statistics | International Metalworking Companies |
| International Meteor Organisation | International Meteorological Organization | International Meteorological Organization Prize |
| International Military Tribunal for the Far East | International Military Tribunal for the Far East Charter | International Military Tribunal Nuremberg |
| International Mind Sports Association | International Mine Clearance Board | International Mine Water Association |
| International Mineralogical Association | International Mister Leather | International Mixed Martial Arts Federation |
| International Mobile Equipment Identity | International Mobile Satellite Organization | International Mobile Subscriber Identity |
| International Mobile Telecommunications | International Mobile Telecommunications 2000 | International Mobile Telecommunications-2000 |
| International Monetary Fund | International Monetary Fund Administrative Tribunal | International Monetary Market |
| International Monitoring System | International Monohull Class Association | International Monohull Open Class Association |
| International Moscow Bank | International Moss Stock Center | International Moth |
| International Moth Class | International Motor Car | International Motor Car Company |
| International Motor Carriage Company | International Motor Cars | International Motor Products |
| International Motor Sports Association | International Motor Vehicle Program | International Motors Cars |
| International Motorsports Hall of Fame | International Mountain Bicycling Association | International Mountain Summit |
| International Movement Against all forms of Discrimination and Racism | International Mr. Leather | International Music |
| International Music Award | International Music Council | International Music Score Library Project |
| International Musicological Society | International N. D. Kondratiev Foundation | International Navigation Chart |
| International Navigation Company | International Near-Earth Asteroid Survey | International Network of Cinemas for the Circulation of European Films |
| International Network of Genocide Scholars | International Network of Street Papers | International Network of Women Engineers and Scientists |
| International Neuroscience Institute | International New Symphony Orchestra Lemberg | International New York Times |
| International News Service | International Newspaper Color Quality Club | International Nickel Company |
| International Noise Conspiracy | International Non-Profit Credit Rating Agency | International non-proprietary name |
| International nonproprietary name | International Nonproprietary Name | International Normalized Ratio |
| International Nuclear Event Scale | International Nuclear Information System | International Nucleotide Sequence Database Collaboration |
| International Numbering System | International Nurses Day | International Obfuscated C Code Contest |
| International Ocean Colour Coordinating Group | International Ocean Discovery Program | International Ocean Institute |
| International Office | International Offshore Rule | International Olympic Committee |
| International Olympic Stadium | International Ombudsman Institute | International Omo Research Expedition |
| International One Frame Shoot-out | International One Frame Shoot-out 1990 | International One Metre |
| International Open | International Open 1981 | International Open 1982 |
| International Open 1983 | International Open 1984 | International Open 1986 |
| International Open 1987 | International Open 1988 | International Open 1989 |
| International Open 1993 | International Open 1994 | International Open 1995 |
| International Open 1996 | International Open 1997 | International Open Source Network |
| International Opera Awards | International Opera Awards 2013 | International Opera Awards 2014 |
| International Opera Awards 2015 | International Opera Awards 2016 | International Opera Awards 2017 |
| International Opera Awards 2018 | International Opera Awards 2019 | International Opera Awards 2020 |
| International Opera Awards 2021 | International Opera Awards 2022 | International Opera Awards 2023 |
| International Organisation for the Study of the Old Testament | International Organisation of Employers | International Organisation of Vine and Wine |
| International Organization for a Participatory Society | International Organization for Migration | International Organization for Septuagint and Cognate Studies |
| International Organization for Standardization | International Organization for Succulent Plant Study | International Organization for the Study of the Old Testament |
| International Organization of Securities Commissions | International Orienteering Federation | International Ornithological Committee |
| International Ornithological Congress | International Ornithological Union | International Ornithologists' Union |
| International Ornithologists’ Union | International Osteoporosis Foundation | International Pablo Casals Cello Competition |
| International Panel for Sustainable Resource Management | International Panel on Chemical Pollution | International Panorama Conference |
| International Panorama Council | International Paper | International Paper Building |
| International Paralympic Committee | International Parcel Service | International Parkinson and Movement Disorder Society |
| International Partnership of Business Schools | International Patent Classification | International Payment Instruction |
| International Peace and Security Institute | International Peace Bureau | International Peace Garden |
| International Peace Garden Airport | International Peace Observers Network | International Peace Research Association |
| International Peacekeeping and Security Center | International PEN | International Pen Friends |
| International Petroleum Exchange | International Petroleum Investment Company | International Pharmaceutical Federation |
| International Pharmaceutical Students' Federation | International Pharmaceutical Students’ Federation | International Phonetic Alphabet |
| International Phonetic Association | International Physicians for the Prevention of Nuclear War | International Physics Olympiad |
