- Aphasia (amnestic) (ataxic) (auditory) (Broca's) (choreatic) (classic) (expressive) (global) (ideational) (ideokinetic) (ideomotor) (jargon) (motor) (nominal) (receptive) (semantic) (sensory) (syntactic) (verbal) (visual) (Wernicke's) 784.3
- Aphemia 784.3
- Aphonia 784.41
- Aphthae, aphthous - see also condition
- Apical - see condition
- Apical ballooning syndrome 429.83
- Aplasia - see also Agenesis
- Apleuria 756.3
- Apnea, apneic (spells) 786.03
- Apneumatosis newborn 770.4
- Apodia 755.31
- Apophysitis (bone) (see also Osteochondrosis) 732.9
- Apoplectiform convulsions (see also Disease, cerebrovascular, acute) 436
- Apoplexia, apoplexy, apoplectic (see also Disease, cerebrovascular, acute) 436
- Appendage
- Appendicitis 541
- Appendiclausis 543.9
- Appendicolithiasis 543.9
- Appendicopathia oxyurica 127.4
- Appendix, appendicular - see also condition
- Appetite
- Apprehension, apprehensiveness (abnormal) (state) 300.00