- Anhidrosis (lid) (neurogenic) (thermogenic) 705.0
- Anhydration 276.51
- Anhydremia 276.52
- Anidrosis 705.0
- Aniridia (congenital) 743.45
- Anisakiasis (infection) (infestation) 127.1
- Anisakis larva infestation 127.1
- Aniseikonia 367.32
- Anisocoria (pupil) 379.41
- Anisocytosis 790.09
- Anisometropia (congenital) 367.31
- Ankle - see condition
- Ankyloblepharon (acquired) (eyelid) 374.46
- Ankylodactly (see also Syndactylism) 755.10
- Ankyloglossia 750.0
- Ankylosis (fibrous) (osseous) 718.50
- Ankylostoma - see Ancylostoma
- Ankylostomiasis (intestinal) - see Ancylostomiasis
- Ankylurethria (see also Stricture, urethra) 598.9
- Annular - see also condition
- Anodontia (complete) (partial) (vera) 520.0
- Anomaly, anomalous (congenital) (unspecified type) 759.9