China 
Africa 
- Avocado
- Avocado oil
- Avoidance
- Avoidance behavior
- Avoidance learning
- Avoidance response
- Avoidant attachment
- Avoidant personality disorder
- Avolition
- Avon Longitudinal Study of Parents and Children
- Avoparcin
- Avulsion fracture
- Avulsion injury
- Avulsions
- Awake craniotomy
- Awareness
- Awe
- Axenfeld-Rieger syndrome
- Axenic
- Axenic culture
- Axial plane
- Axial skeleton
- Axial spondyloarthritis
- Axicabtagene ciloleucel
- Axillary
- Axillary artery
- Axillary dissection
- Axillary fascia
- Axillary lines
- Axillary lymph nodes
- Axillary lymphadenopathy
- Axillary nerve
- Axillary nerve palsy
- Axillary sheath
- Axillary vein
- Axitinib
- Axolemma
- Axon guidance
- Axon hillock
- Axon reflex
- Axon terminal
- Axonal
- Axoneme
- Axonotmesis
- Axoplasm
- Axoplasmic transport
- Axotomy
- Ayahuasca
- Ayre spatula
- Ayurveda
- Ayurvedic medicine
- Azacitidine
- Azacyclonol
- Azalide
- Azasteroid
- Azathioprine
- Azelaic acid
- Azelastine
- Azetidine
- Azetidine 2 carboxylic acid
- Azetidines
- Azide
- Azilsartan
- Azilsartan medoxomil
- Azimilide
- Azine
- Azinphos methyl
- Azinphos-methyl
- Aziridine
- Aziridines
- Azithromycin
- Azo compounds
- Azo dyes
- Azo reductase
- Azobenzene
- Azobilirubin
- Azobisisobutyronitrile
- Azoles
- Azoospermia
- Azoospermia factor
- Azospirillum
- Azotemia
- Azotobacter
- Azoxy compounds
- Azoxymethane
- Aztreonam
- Aztreonam lysine
- Azulene
- Azure A
- Azurin
- Azurophil
- Azurophilic granules
- Azvudine
- Azygos
- Azygos vein
- B cell activating factor
- B cell leukemia
- B cell lymphoma
- B cell maturation antigen
- B cell receptor
- B cells
- B chromosomes
- B lymphocytes
- B symptoms
- B virus
- B vitamins
- B-Lynch suture
- B-cell activating factor
- B-cell linker
- B-cell lymphoma
- B-cell prolymphocytic leukemia
- B-cell receptor
- B-cells
- B-scan
- B-scan ultrasonography
- B7
- BAC
- BACE1-AS
- BACH2
- BAEP
- BAFF receptor
- BALT
- BAP1
- BAPTA
- BASDAI
- BASFI
- BATF2
- BBSome
- BCG vaccination
- BCG vaccine
- BCKDHA
- BCKDK
- BCL6
- BCR
- BCR gene
- BDNF
- BEACOPP
- BEAMing
- BECN1
- BED
- BHLHE41
- BHMT
- BI-RADS
- BIA 10-2474
- BIC
- BIM-1
- BK channel
- BLA
- BLAT
- BMI