Medical Organizations
- International Council on Social Welfare (ICSF)
- International Cystic Fibrosis (Mucoviscidosis) Association (ICFMA)
- International Dental Federation (IDF)
- International Dental Organization (IDO)
- International Diabetes Federation (IDF)
- International Documentation Society for Chemistry (IDC)
- International Dyslexia Association (IDA)
- Internationale Gesellschaft fur Allgemeinmedizin; International Society of General Medicine (IGAM)
- Internationale Gesellschaft fur Chemo- und Immuntherapie; International Society of Chemotherapy and Immunotherapy (IGCI)
- Internationale Gesellschaft fur Prospektive Medizin; International Society for Prospective Medicine (IGPM)
- Internationale Gesellschaft fur Radiobiologie; International Society of Radiobiology (IGR)
- Internationale Kommission für Alpines Rettungswesen; International Commission for Alpine Rescue (IKAR)
- International Epidemiological Association (IEA)
- International Exhibition of Laboratory Technique, Measuring, and Automation in Chemistry (ILMAC)
- International Expressive Arts Therapy Association (IEATA)
- International Family Therapy Association (IFTA)
- International Federation for Medical and Biological Engineering (IFMBE)
- International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO)
- International Federation of Associations of Pharmaceutical Physicians (IFAPP)
- International Federation of Cervical Pathology and Colposcopy (IFCPC)
- International Federation of Chromatography (IFC)
- International Federation of Clinical Chemistry (IFCC)
- International Federation of Eating Disorder Dietitians (IFEDD)
- International Federation of Electro-Encephalographical Societies (IFEES)
- International Federation of Fertility Societies (IFFS)
- International Federation of Gynecology and Obstetrics (IFGO)
- International Federation of Health Information Management Associations (IFHIMA)
- International Federation of Medical Electronics (IFME)
- International Federation of Medical Psychotherapy (IFMP)
- International Federation of Medical Students' Associations (IFMSA)
- International Federation of Multiple Sclerosis Societies (IFMSS)
- International Federation of Operational Research Societies (IFORS)
- International Federation of Otorhinolaryngological Societies (IFOS)
- International Federation of Pharmaceutical Manufacturers Associations (IFPMA)
- International Federation of Physical Medicine (IFPM)
- International Federation of Societies for Electroencephalography and Clinical Neurophysiology (IFSECN)
- International Federation of Societies for Electron Microscopy (IFSEM)
- International Fertility Research Program (IFRP)
- International Foot and Ankle Foundation (IFAF)
- International Foundation for Nutrition and Health (IFNH)
- International Headache Society (IHS)
- International Health Conference (IHC)
- International Health Economics and Management Institute (IHEMI)
- International Health Foundation (IHF)
- International Health Organization (IHO)
- International Hearing Society (IHS)
- International Hemophilia Society (IHS)
- International Hospital Association (IHA)
- International Hospital Federation (IHF)
- International Institute for Applied System Analysis (IIASA)
- International Institute of Anthropology (IIA)
- International Institute of Embryology (IIE)
- International Institute of Medical Electronics and Biological Engineering (IIMEBE)
- International Institute of Reflexology (IIR)
- International Institute of Sociology (IIS)
- International Lactation Consultant Association (ILCA)
- International League against Epilepsy (ILAE)
- International League against Rheumatism (ILAR)
- International Leprosy Association (ILA)
- International Lyme and Associated Diseases Society (ILADS)
- International Lymphedema & Wound Training Institute (ILWTI)
- International Medical Corporation (IMC)
- International Menopause Society (Belgium) (IMS)
- International Neurological Association (INA)
- International Neuromodulation Society (INS)
- International Neuropsychological Society (INS)
- International Nurses Society on Addictions (IntNSA)
- International OCD Foundation (IOCDF)
- International Organization Against Trachoma (IOAT)
- International Organization for Medical Physics (IOMP)
- International Organization for Pure and Applied Biophysics (IOPAB)
- International Organization of Standardization (IOS)
- International Parkinson and Movement Disorder Society (MDS)
- International Pediatric Nephrology Association (IPNA)
- International Peeling Society (IPS)
- International Pelvic Pain Society (IPPS)
- International Pharmaceutical Federation (IPF)
- International Pharmaceutical Students' Federation (IPSF)
- International Physicians for Prevention of Nuclear Warfare (IPPNW)
- International Placenta & Postpartum Association (IPPA)
- International Planned Parenthood Federation (IPPF)
- International Poliomyelitis Congress (IPC)
- International Positive Psychology Association (IPPA)
- International Program on Chemical Safety (IPCS)
- International Prospective Primary Prevention Study in Hypertension (IPPPSH)
- International Psychoanalytical Association (IPA)
- International Psychological Congress (IPC)
- International Radiation Protection Association (IRPA)
- International Red Cross (IRC)
- International Red Cross Committee (IRCC)
- International Reiki Organization (IRO)
- International Research Communication System (IRCS)
- International Research Group for Carcinoembryonic Proteins (IRGCP)
- International Society for Artificial Organs (ISAO)
- International Society for Biological Therapy of Cancer (iSBTc)
- International Society for Clinical and Experimental Hypnosis (ISCEH)
- International Society for Clinical Electroretinography (ISCERG)
- International Society for Clinical Laboratory Technology (ISCLT)
- International Society for Dermatologic Surgery (ISDS)
- International Society for Environmentally Acquired Illness (ISEAI)