- Interferon alfa 2b
- Interferon beta-1a
- Interferon beta-1b
- Interferon gamma
- Interferon gamma release assay
- Interferon regulatory factors
- Interferon stimulated gene factor 3
- Interferon tau
- Interferon type I
- Interferon-gamma receptor
- Interferons
- Intergenerational equity
- Intergenic region
- Intergluteal cleft
- Intergroup bias
- Intergroup relations
- Interim analysis
- Interleukin
- Interleukin 1
- Interleukin 1 receptor antagonist
- Interleukin 1-alpha
- Interleukin 10
- Interleukin 11
- Interleukin 12
- Interleukin 13
- Interleukin 15
- Interleukin 17
- Interleukin 18
- Interleukin 1beta
- Interleukin 2
- Interleukin 2 receptor
- Interleukin 21
- Interleukin 22
- Interleukin 23
- Interleukin 25
- Interleukin 3
- Interleukin 31
- Interleukin 32
- Interleukin 33
- Interleukin 36
- Interleukin 4
- Interleukin 5
- Interleukin 6
- Interleukin 7
- Interleukin 8
- Interleukin-1 receptor associated kinase
- Interleukin-23 receptor
- Interleukin-3 receptor
- Interleukin-4 receptor
- Interleukin-5 receptor
- Interleukin-7 receptor
- Interleukin-7 receptor-α
- Interleukins
- Interlobar arteries
- Interlobular arteries
- Interlobular bile ducts
- Interlobular veins
- Intermediate dorsal cutaneous nerve
- Intermediate filaments
- Intermediate hosts
- Intermediate mesoderm
- Intermediate nerve
- Intermediate trophoblast
- Intermediate uveitis
- Intermediate-density lipoprotein
- Intermediolateral nucleus
- Intermembrane space
- Intermetamorphosis
- Intermittent catheterisation
- Intermittent claudication
- Intermittent fasting
- Intermittent fever
- Intermittent hypoxia
- Intermittent mandatory ventilation
- Intermittent photic stimulation
- Intermittent pneumatic compression
- Intermittent reinforcement
- Intermittent rhythmic delta activity
- Intermuscular coherence
- Internal
- Internal anal sphincter
- Internal auditory canal
- Internal auditory meatus
- Internal bleeding
- Internal capsule
- Internal carotid artery
- Internal cerebral veins
- Internal clock
- Internal conversion
- Internal dosimetry
- Internal elastic lamina
- Internal environment
- Internal fixation
- Internal granular layer
- Internal iliac artery
- Internal iliac lymph node
- Internal iliac vein
- Internal intercostal
- Internal intercostal muscles
- Internal jugular vein
- Internal limiting membrane
- Internal locus of control
- Internal mammary artery
- Internal medicine
- Internal migration
- Internal models
- Internal oblique muscle
- Internal occipital crest
- Internal occipital protuberance
- Internal pudendal artery
- Internal pudendal vein
- Internal pudendal veins
- Internal spermatic fascia
- Internal standard
- Internal thoracic artery
- Internal thoracic vein
- Internal urethral orifice
- Internal urethral sphincter
- Internal validity
- Internal working model of attachment
- Internalin
- Internalization
- Internalized racism
- International Affective Picture System
- International Classification of Diseases
- International Classification of Functioning, Disability and Health
- International Classification of Headache Disorders
- International Classification of Primary Care
- International Classification of Sleep Disorders
- International Clinical Trials Registry Platform
- International Code of Marketing of Breast-milk Substitutes
- International Conference on Population and Development
- International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use
- International HapMap Project
- International Menopause Society
- International Nomenclature of Cosmetic Ingredients
- International Prognostic Index
- International Society of Biomechanics
- International Subarachnoid Aneurysm Trial
- International nonproprietary name
- International prostate symptom score
- Internet addiction disorder
- Interneurons
- Internuclear ophthalmoplegia
- Interoception
- Interossei
- Interosseous muscles of the hand
- Interpeduncular cistern
- Interpeduncular fossa
- Interpeduncular nucleus