- 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 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 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
- Interpersonal Neurobiology
- Interpersonal Psychotherapy
- Interpersonal Reactivity Index
- Interpersonal and Social Rhythm Therapy
- Interpersonal intelligence
- Interpersonal trauma
- Interpersonal violence
- Interphalangeal
- Interphalangeal joint
- Interphalangeal joints
- Interphase
- Interpolymer complexes
- Interprofessional education
- Interrater reliability
- Interrupted aortic arch
- Interrupted time series
- Interruptions
- Intersegmental artery
- Intersex
- Intersex human rights
- Interspersed repeat
- Interspinous ligament
- Interstimulus interval
- Interstitial
- Interstitial cells
- Interstitial cells of Cajal
- Interstitial cystitis
- Interstitial fluid
- Interstitial keratitis
- Interstitial lung disease
- Interstitial nephritis
- Interstitial pneumonia
- Interstitial pregnancy
- Intertransverse ligament
- Intertransverse ligaments
- Intertriginous
- Intertrigo
- Intertrochanteric crest
- Intertrochanteric line
- Interval training
- Interventional cardiology
- Interventional neuroradiology
- Interventional pain management
- Interventional pulmonology
- Interventional radiology
- Interventricular septum
- Intervertebral disc
- Intervertebral disk
- Intervertebral foramen
- Intervertebral foramina
- Intervertebral vein
- Intervertebral veins
- Intervillous space
- Intestinal arteries
- Intestinal atresia
- Intestinal bypass