- Shutdown
- Shwachman's syndrome 288.02
- Shy-Drager syndrome (orthostatic hypotension with multisystem degeneration) 333.0
- Sialadenitis (any gland) (chronic) (supportive) 527.2
- Sialadenosis, periodic 527.2
- Sialaporia 527.7
- Sialectasia 527.8
- Sialitis 527.2
- Sialoadenitis (see also Sialadenitis) 527.2
- Sialoangitis 527.2
- Sialodochitis (fibrinosa) 527.2
- Sialodocholithiasis 527.5
- Sialolithiasis 527.5
- Sialorrhea (see also Ptyalism) 527.7
- Sialosis 527.8
- Siamese twin 759.4
- Sicard's syndrome 352.6
- Sicca syndrome (keratoconjunctivitis) 710.2
- Sick 799.9
- Sick sinus syndrome 427.81
- Sickle-cell
- Sicklemia (see also Disease, sickle-cell) 282.60