China 
Africa 
- Achilles tendon rupture
- Achlorhydria
- Acholeplasma
- Acholeplasma laidlawii
- Achondrogenesis
- Achondrogenesis type 1B
- Achondrogenesis type 1b
- Achondroplasia
- Achromatopsia
- Achromobacter
- Achromobacter xylosoxidans
- Aci-Jel
- Aciclovir
- Acid
- Acid anhydrides
- Acid catalysis
- Acid citrate dextrose
- Acid dissociation constant
- Acid dyes
- Acid erosion
- Acid gas
- Acid guanidinium thiocyanate-phenol-chloroform extraction
- Acid hydrolase
- Acid hydrolases
- Acid mantle
- Acid number
- Acid phosphatase
- Acid precipitation
- Acid salts
- Acid sensing ion channels
- Acid sphingomyelinase
- Acid strength
- Acid value
- Acid-base balance
- Acid-base disorders
- Acid-base homeostasis
- Acid-base imbalance
- Acid-base indicator
- Acid-base reactions
- Acid-base titration
- Acid-citrate-dextrose
- Acid-fast
- Acid-sensing ion channels
- Acidaminococcus
- Acidemia
- Acidification
- Acidifiers
- Acidity
- Acidogenesis
- Acidophiles
- Acidophilus milk
- Acidosis
- Acidulants
- Aciduria
- Acinar
- Acinar cells
- Acinetobacter
- Acinetobacter baumannii
- Acinetobacter calcoaceticus
- Acini
- Acinic cell carcinoma
- Acipimox
- Acitretin
- Aclarubicin
- Aclidinium bromide
- Acmella oleracea
- Acne
- Acne conglobata
- Acne fulminans
- Acne keloidalis nuchae
- Acne vulgaris
- Acneiform eruptions
- Aconitase
- Aconite
- Aconitic acid
- Aconitine
- Aconitum
- Aconitum carmichaelii
- Acorus calamus
- Acoustic droplet ejection
- Acoustic neuroma
- Acoustic radiation
- Acoustic radiation force impulse imaging
- Acoustic reflex
- Acoustic rhinometry
- Acoustic trauma
- Acoustics
- Acousto-optic modulators
- Acquired brain injury
- Acquired hemolytic anemia
- Acquired ichthyosis
- Acquired immunity
- Acquired immunodeficiency syndrome
- Acquired pendular nystagmus
- Acral lentiginous melanoma
- Acrania
- Acridine
- Acridine orange
- Acriflavine
- Acroangiodermatitis
- Acrocallosal syndrome
- Acrocyanosis
- Acrodermatitis
- Acrodermatitis chronica atrophicans
- Acrodermatitis enteropathica
- Acrodynia
- Acrodysostosis
- Acrogeria
- Acrokeratosis paraneoplastica of Bazex
- Acrolein
- Acromegaly
- Acromioclavicular dislocation
- Acromioclavicular joint
- Acromioclavicular ligament
- Acromion
- Acromioplasty
- Acropachy
- Acrophobia
- Acroplaxome
- Acropustulosis
- Acrosin
- Acrosome
- Acrosome reaction
- Acrospiroma
- Acrylamide
- Acrylates
- Acrylic acid
- Acrylic polymer
- Acrylonitrile
- Actaea racemosa
- Actigraph
- Actigraphy
- Actimetry
- Actin binding proteins
- Actin depolymerizing factor
- Actin filaments
- Actin polymerization
- Actin remodeling
- Actin-binding proteins
- Acting out
- Actinic cheilitis
- Actinic keratosis
- Actinic prurigo
- Actinide
- Actinidia chinensis
- Actinidin
- Actinin
- Actinism
- Actinium-225
- Actinobacillus