- Immunomagnetic separation
- Immunometabolism
- Immunomics
- Immunomodulation
- Immunomodulatory drug
- Immunopathology
- Immunoperoxidase
- Immunophenotyping
- Immunoproteasome
- Immunoproteomics
- Immunoreceptor tyrosine-based activation motif
- Immunoreceptor tyrosine-based inhibitory motif
- Immunoregulation
- Immunoscintigraphy
- Immunoscore
- Immunosenescence
- Immunostaining
- Immunostimulant
- Immunosuppressants
- Immunosuppression
- Immunosuppressive agent
- Immunosuppressive drugs
- Immunosurveillance
- Immunotherapy
- Immunotoxicity
- Immunotoxicology
- Immunotoxins
- Imp321
- Impact bias
- Impacted
- Impacted wisdom teeth
- Impaction
- Impaired glucose tolerance
- Impedance
- Impedance cardiography
- Impedance plethysmography
- Impedance-pH monitoring
- Impella
- Imperatorin
- Imperforate anus
- Imperforate hymen
- Impetigo
- Impetigo herpetiformis
- Implant Stability Quotient
- Implant failure
- Implantable loop recorder
- Implantation
- Implants
- Implementation intention
- Implicit attitudes
- Implicit cognition
- Implicit memory
- Implicit-association test
- Implosive therapy
- Importin
- Importin α
- Imposex
- Impostor syndrome
- Impotence
- Impregnation
- Impression management
- Imprinting
- Improved sanitation
- Improving Access to Psychological Therapies
- Impulse control disorder
- Impulsiveness
- Impulsivity
- Imputation
- In case of emergency
- In ovo
- In silico
- In situ conservation
- In situ hybridization
- In vitro
- In vitro fertilisation
- In vitro to in vivo extrapolation
- In vitro toxicology
- In vivo
- In vivo bioreactor
- In-gel digestion
- Inactivated vaccine
- Inactivated virus vaccine
- Inactivation
- Inappropriate sinus tachycardia
- Inattentional blindness
- Inborn errors of immunity
- Inborn errors of metabolism
- Inbred strains
- Inbreeding
- Inbreeding depression
- Incentive spirometer
- Incentive spirometry
- Incentivisation
- Incest
- Incident angle
- Incidental findings
- Incineration
- Incision
- Incision and drainage
- Incisional hernia
- Incisive canal
- Incisive canals
- Incisive foramen
- Incisive foramina
- Incisive papilla
- Incisors
- Inclisiran
- Inclusion
- Inclusion and exclusion criteria
- Inclusion bodies
- Inclusion body myositis
- Incomplete abortion
- Incomplete combustion
- Incomplete dominance
- Incontinence
- Incontinentia pigmenti
- Increased appetite
- Incremental exercise
- Incretin
- Incubation
- Incubation time
- Incudostapedial joint
- Incus
- Indacaterol
- Indapamide
- Indazole
- Indecent exposure
- Indels
- Independent living
- Independent variable
- Indeterminacy
- Index finger
- Indiana pouch
- Indican
- Indications
- Indicator species
- Indicators
- Indigestion
- Indigo carmine
- Indirect DNA damage
- Indirect agonist
- Indirect calorimetry
- Indirect inguinal hernia
- Indirubin
- Indisulam
- Indium 111
- Indium antimonide
- Indium gallium arsenide
- Indium oxide
- Indium phosphide