- Ballooning posterior leaflet syndrome 424.0
- Baló's disease or concentric sclerosis 341.1
- Bamberger's disease (hypertrophic pulmonary osteoarthropathy) 731.2
- Bamberger-Marie disease (hypertrophic pulmonary osteoarthropathy) 731.2
- Bamboo spine 720.0
- Bancroft's filariasis 125.0
- Band(s)
- Bandemia (without diagnosis of specific infection) 288.66
- Bandl's ring (contraction)
- Bang's disease (Brucella abortus) 023.1
- Bangkok hemorrhagic fever 065.4
- Bannister's disease 995.1
- Bantam-Albright-Martin disease (pseudohypoparathyroidism) 275.49
- Banti's disease or syndrome (with cirrhosis) (with portal hypertension) - see Cirrhosis, liver
- Bar
- Baragnosis 780.99
- Barasheh, barashek 266.2
- Barcoo disease or rot (see also Ulcer, skin) 707.9
- Bard-Pic syndrome (carcinoma, head of pancreas) 157.0
- Bärensprung's disease (eczema marginatum) 110.3
- Baritosis 503
- Barium lung disease 503
