- Body, bodies
- Boeck's
- Boerhaave's syndrome (spontaneous esophageal rupture) 530.4
- Boggy
- Boil (see also Carbuncle) 680.9
- Bold hives (see also Urticaria) 708.9
- Bolivian hemorrhagic fever 078.7
- Bombé, iris 364.74
- Bomford-Rhoads anemia (refractory) 238.72
- Bone - see condition
- Bonnevie-Ullrich syndrome 758.6
- Bonnier's syndrome 386.19
- Bonvale Dam fever 780.79
- Bony block of joint 718.80
- Borderline
- Borna disease 062.9
- Bornholm disease (epidemic pleurodynia) 074.1
- Borrelia vincentii (mouth) (pharynx) (tonsils) 101
- Bostock's catarrh (see also Fever, hay) 477.9
- Boston exanthem 048
- Botalli, ductus (patent) (persistent) 747.0
- Bothriocephalus latus infestation 123.4