China 
Africa 
- Atresia
- Atrial
- Atrial enlargement
- Atrial fibrillation
- Atrial flutter
- Atrial function
- Atrial myxoma
- Atrial natriuretic factor
- Atrial septal defect
- Atrial switch
- Atrial tachycardia
- Atrioventricular block
- Atrioventricular canal
- Atrioventricular nodal reentrant tachycardia
- Atrioventricular nodal reentry tachycardia
- Atrioventricular node
- Atrioventricular septal defect
- Atrioventricular septum
- Atripla
- Atropa
- Atropa belladonna
- Atrophic gastritis
- Atrophic glossitis
- Atrophic rhinitis
- Atrophic vaginitis
- Atrophy
- Atropine
- Atryn
- Attachment disorder
- Attachment in adults
- Attachment in children
- Attachment insecurity
- Attachment parenting
- Attachment style
- Attachment theory
- Attack rate
- Attapulgite
- Attempted rape
- Attention
- Attention Restoration Theory
- Attention deficit
- Attention deficit hyperactivity disorder predominantly inattentive
- Attention economy
- Attentional bias
- Attentional control
- Attentional shift
- Attenuated familial adenomatous polyposis
- Attenuated vaccine
- Attenuation
- Attenuation coefficient
- Attractants
- Attributable fraction for the population
- Attributable risk
- Attribution bias
- Attunement
- Atypia
- Atypical anorexia nervosa
- Atypical antidepressants
- Atypical antipsychotics
- Atypical chronic myeloid leukemia
- Atypical depression
- Atypical ductal hyperplasia
- Atypical facial pain
- Atypical fibroxanthoma
- Atypical hemolytic uremic syndrome
- Atypical hyperplasia
- Atypical pneumonia
- Atypical small acinar proliferation
- Atypical teratoid rhabdoid tumor
- Atypical trigeminal neuralgia
- Aucubin
- Audiogram
- Audiologist
- Audiology
- Audiometer
- Audiometry
- Auditory agnosia
- Auditory brain stem implant
- Auditory brainstem implant
- Auditory bulla
- Auditory canal
- Auditory cortex
- Auditory evoked potential
- Auditory fatigue
- Auditory feedback
- Auditory hallucinations
- Auditory learning
- Auditory masking
- Auditory memory
- Auditory nerve
- Auditory neuropathy
- Auditory neuropathy spectrum disorder
- Auditory ossicles
- Auditory perception
- Auditory processing disorder
- Auditory scene analysis
- Auditory stimuli
- Auditory system
- Auditory threshold
- Auditory tube
- Auditory verbal therapy
- Audits
- Auer rods
- Auerbach's plexus
- Augmentation
- Augmentative and alternative communication
- Augmented renal clearance
- Aura
- Aural rehabilitation
- Auramine
- Auramine O
- Auranofin
- Auraptene
- Auras
- Aureobasidium pullulans
- Aureolysin
- Auricle
- Auricular branch
- Auricular muscles
- Auriculotemporal nerve
- Auriculotherapy
- Aurintricarboxylic acid
- Aurora A kinase
- Aurora B
- Aurora B kinase
- Aurora kinase
- Aurora kinase inhibitor
- Aurothioglucose
- Auscultation
- Auscultatory gap
- Auspitz's sign
- Autacoids
- Authentic Movement
- Authoritarian personality
- Autism
- Autism Diagnostic Interview Revised
- Autism Diagnostic Observation Schedule
- Autism spectrum
- Autism spectrum disorders
- Autism-friendly
- Autoagglutination
- Autoantibodies
- Autoantibody
- Autoantigens
- Autobiographical memory
- Autocatalysis
- Autoclave
- Autoclaving
- Autocoids
- Autocomplete